Initial import

1 files changed, 4265 insertions, 0 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
new file mode 100644
index 000000000..ee2e188e1
--- /dev/null
+++ b/drivers/ata/libata-eh.c
@@ -0,0 +1,4265 @@
+/*
+ *  libata-eh.c - libata error handling
+ *
+ *  Maintained by:  Tejun Heo <tj@kernel.org>
+ *    		    Please ALWAYS copy linux-ide@vger.kernel.org
+ *		    on emails.
+ *
+ *  Copyright 2006 Tejun Heo <htejun@gmail.com>
+ *
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License as
+ *  published by the Free Software Foundation; either version 2, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; see the file COPYING.  If not, write to
+ *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
+ *  USA.
+ *
+ *
+ *  libata documentation is available via 'make {ps|pdf}docs',
+ *  as Documentation/DocBook/libata.*
+ *
+ *  Hardware documentation available from http://www.t13.org/ and
+ *  http://www.sata-io.org/
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/blkdev.h>
+#include <linux/export.h>
+#include <linux/pci.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_dbg.h>
+#include "../scsi/scsi_transport_api.h"
+
+#include <linux/libata.h>
+
+#include <trace/events/libata.h>
+#include "libata.h"
+
+enum {
+	/* speed down verdicts */
+	ATA_EH_SPDN_NCQ_OFF		= (1 << 0),
+	ATA_EH_SPDN_SPEED_DOWN		= (1 << 1),
+	ATA_EH_SPDN_FALLBACK_TO_PIO	= (1 << 2),
+	ATA_EH_SPDN_KEEP_ERRORS		= (1 << 3),
+
+	/* error flags */
+	ATA_EFLAG_IS_IO			= (1 << 0),
+	ATA_EFLAG_DUBIOUS_XFER		= (1 << 1),
+	ATA_EFLAG_OLD_ER                = (1 << 31),
+
+	/* error categories */
+	ATA_ECAT_NONE			= 0,
+	ATA_ECAT_ATA_BUS		= 1,
+	ATA_ECAT_TOUT_HSM		= 2,
+	ATA_ECAT_UNK_DEV		= 3,
+	ATA_ECAT_DUBIOUS_NONE		= 4,
+	ATA_ECAT_DUBIOUS_ATA_BUS	= 5,
+	ATA_ECAT_DUBIOUS_TOUT_HSM	= 6,
+	ATA_ECAT_DUBIOUS_UNK_DEV	= 7,
+	ATA_ECAT_NR			= 8,
+
+	ATA_EH_CMD_DFL_TIMEOUT		=  5000,
+
+	/* always put at least this amount of time between resets */
+	ATA_EH_RESET_COOL_DOWN		=  5000,
+
+	/* Waiting in ->prereset can never be reliable.  It's
+	 * sometimes nice to wait there but it can't be depended upon;
+	 * otherwise, we wouldn't be resetting.  Just give it enough
+	 * time for most drives to spin up.
+	 */
+	ATA_EH_PRERESET_TIMEOUT		= 10000,
+	ATA_EH_FASTDRAIN_INTERVAL	=  3000,
+
+	ATA_EH_UA_TRIES			= 5,
+
+	/* probe speed down parameters, see ata_eh_schedule_probe() */
+	ATA_EH_PROBE_TRIAL_INTERVAL	= 60000,	/* 1 min */
+	ATA_EH_PROBE_TRIALS		= 2,
+};
+
+/* The following table determines how we sequence resets.  Each entry
+ * represents timeout for that try.  The first try can be soft or
+ * hardreset.  All others are hardreset if available.  In most cases
+ * the first reset w/ 10sec timeout should succeed.  Following entries
+ * are mostly for error handling, hotplug and those outlier devices that
+ * take an exceptionally long time to recover from reset.
+ */
+static const unsigned long ata_eh_reset_timeouts[] = {
+	10000,	/* most drives spin up by 10sec */
+	10000,	/* > 99% working drives spin up before 20sec */
+	35000,	/* give > 30 secs of idleness for outlier devices */
+	 5000,	/* and sweet one last chance */
+	ULONG_MAX, /* > 1 min has elapsed, give up */
+};
+
+static const unsigned long ata_eh_identify_timeouts[] = {
+	 5000,	/* covers > 99% of successes and not too boring on failures */
+	10000,  /* combined time till here is enough even for media access */
+	30000,	/* for true idiots */
+	ULONG_MAX,
+};
+
+static const unsigned long ata_eh_flush_timeouts[] = {
+	15000,	/* be generous with flush */
+	15000,  /* ditto */
+	30000,	/* and even more generous */
+	ULONG_MAX,
+};
+
+static const unsigned long ata_eh_other_timeouts[] = {
+	 5000,	/* same rationale as identify timeout */
+	10000,	/* ditto */
+	/* but no merciful 30sec for other commands, it just isn't worth it */
+	ULONG_MAX,
+};
+
+struct ata_eh_cmd_timeout_ent {
+	const u8		*commands;
+	const unsigned long	*timeouts;
+};
+
+/* The following table determines timeouts to use for EH internal
+ * commands.  Each table entry is a command class and matches the
+ * commands the entry applies to and the timeout table to use.
+ *
+ * On the retry after a command timed out, the next timeout value from
+ * the table is used.  If the table doesn't contain further entries,
+ * the last value is used.
+ *
+ * ehc->cmd_timeout_idx keeps track of which timeout to use per
+ * command class, so if SET_FEATURES times out on the first try, the
+ * next try will use the second timeout value only for that class.
+ */
+#define CMDS(cmds...)	(const u8 []){ cmds, 0 }
+static const struct ata_eh_cmd_timeout_ent
+ata_eh_cmd_timeout_table[ATA_EH_CMD_TIMEOUT_TABLE_SIZE] = {
+	{ .commands = CMDS(ATA_CMD_ID_ATA, ATA_CMD_ID_ATAPI),
+	  .timeouts = ata_eh_identify_timeouts, },
+	{ .commands = CMDS(ATA_CMD_READ_NATIVE_MAX, ATA_CMD_READ_NATIVE_MAX_EXT),
+	  .timeouts = ata_eh_other_timeouts, },
+	{ .commands = CMDS(ATA_CMD_SET_MAX, ATA_CMD_SET_MAX_EXT),
+	  .timeouts = ata_eh_other_timeouts, },
+	{ .commands = CMDS(ATA_CMD_SET_FEATURES),
+	  .timeouts = ata_eh_other_timeouts, },
+	{ .commands = CMDS(ATA_CMD_INIT_DEV_PARAMS),
+	  .timeouts = ata_eh_other_timeouts, },
+	{ .commands = CMDS(ATA_CMD_FLUSH, ATA_CMD_FLUSH_EXT),
+	  .timeouts = ata_eh_flush_timeouts },
+};
+#undef CMDS
+
+static void __ata_port_freeze(struct ata_port *ap);
+#ifdef CONFIG_PM
+static void ata_eh_handle_port_suspend(struct ata_port *ap);
+static void ata_eh_handle_port_resume(struct ata_port *ap);
+#else /* CONFIG_PM */
+static void ata_eh_handle_port_suspend(struct ata_port *ap)
+{ }
+
+static void ata_eh_handle_port_resume(struct ata_port *ap)
+{ }
+#endif /* CONFIG_PM */
+
+static void __ata_ehi_pushv_desc(struct ata_eh_info *ehi, const char *fmt,
+				 va_list args)
+{
+	ehi->desc_len += vscnprintf(ehi->desc + ehi->desc_len,
+				     ATA_EH_DESC_LEN - ehi->desc_len,
+				     fmt, args);
+}
+
+/**
+ *	__ata_ehi_push_desc - push error description without adding separator
+ *	@ehi: target EHI
+ *	@fmt: printf format string
+ *
+ *	Format string according to @fmt and append it to @ehi->desc.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+void __ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	__ata_ehi_pushv_desc(ehi, fmt, args);
+	va_end(args);
+}
+
+/**
+ *	ata_ehi_push_desc - push error description with separator
+ *	@ehi: target EHI
+ *	@fmt: printf format string
+ *
+ *	Format string according to @fmt and append it to @ehi->desc.
+ *	If @ehi->desc is not empty, ", " is added in-between.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+void ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
+{
+	va_list args;
+
+	if (ehi->desc_len)
+		__ata_ehi_push_desc(ehi, ", ");
+
+	va_start(args, fmt);
+	__ata_ehi_pushv_desc(ehi, fmt, args);
+	va_end(args);
+}
+
+/**
+ *	ata_ehi_clear_desc - clean error description
+ *	@ehi: target EHI
+ *
+ *	Clear @ehi->desc.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+void ata_ehi_clear_desc(struct ata_eh_info *ehi)
+{
+	ehi->desc[0] = '\0';
+	ehi->desc_len = 0;
+}
+
+/**
+ *	ata_port_desc - append port description
+ *	@ap: target ATA port
+ *	@fmt: printf format string
+ *
+ *	Format string according to @fmt and append it to port
+ *	description.  If port description is not empty, " " is added
+ *	in-between.  This function is to be used while initializing
+ *	ata_host.  The description is printed on host registration.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_port_desc(struct ata_port *ap, const char *fmt, ...)
+{
+	va_list args;
+
+	WARN_ON(!(ap->pflags & ATA_PFLAG_INITIALIZING));
+
+	if (ap->link.eh_info.desc_len)
+		__ata_ehi_push_desc(&ap->link.eh_info, " ");
+
+	va_start(args, fmt);
+	__ata_ehi_pushv_desc(&ap->link.eh_info, fmt, args);
+	va_end(args);
+}
+
+#ifdef CONFIG_PCI
+
+/**
+ *	ata_port_pbar_desc - append PCI BAR description
+ *	@ap: target ATA port
+ *	@bar: target PCI BAR
+ *	@offset: offset into PCI BAR
+ *	@name: name of the area
+ *
+ *	If @offset is negative, this function formats a string which
+ *	contains the name, address, size and type of the BAR and
+ *	appends it to the port description.  If @offset is zero or
+ *	positive, only name and offsetted address is appended.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_port_pbar_desc(struct ata_port *ap, int bar, ssize_t offset,
+			const char *name)
+{
+	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
+	char *type = "";
+	unsigned long long start, len;
+
+	if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM)
+		type = "m";
+	else if (pci_resource_flags(pdev, bar) & IORESOURCE_IO)
+		type = "i";
+
+	start = (unsigned long long)pci_resource_start(pdev, bar);
+	len = (unsigned long long)pci_resource_len(pdev, bar);
+
+	if (offset < 0)
+		ata_port_desc(ap, "%s %s%llu@0x%llx", name, type, len, start);
+	else
+		ata_port_desc(ap, "%s 0x%llx", name,
+				start + (unsigned long long)offset);
+}
+
+#endif /* CONFIG_PCI */
+
+static int ata_lookup_timeout_table(u8 cmd)
+{
+	int i;
+
+	for (i = 0; i < ATA_EH_CMD_TIMEOUT_TABLE_SIZE; i++) {
+		const u8 *cur;
+
+		for (cur = ata_eh_cmd_timeout_table[i].commands; *cur; cur++)
+			if (*cur == cmd)
+				return i;
+	}
+
+	return -1;
+}
+
+/**
+ *	ata_internal_cmd_timeout - determine timeout for an internal command
+ *	@dev: target device
+ *	@cmd: internal command to be issued
+ *
+ *	Determine timeout for internal command @cmd for @dev.
+ *
+ *	LOCKING:
+ *	EH context.
+ *
+ *	RETURNS:
+ *	Determined timeout.
+ */
+unsigned long ata_internal_cmd_timeout(struct ata_device *dev, u8 cmd)
+{
+	struct ata_eh_context *ehc = &dev->link->eh_context;
+	int ent = ata_lookup_timeout_table(cmd);
+	int idx;
+
+	if (ent < 0)
+		return ATA_EH_CMD_DFL_TIMEOUT;
+
+	idx = ehc->cmd_timeout_idx[dev->devno][ent];
+	return ata_eh_cmd_timeout_table[ent].timeouts[idx];
+}
+
+/**
+ *	ata_internal_cmd_timed_out - notification for internal command timeout
+ *	@dev: target device
+ *	@cmd: internal command which timed out
+ *
+ *	Notify EH that internal command @cmd for @dev timed out.  This
+ *	function should be called only for commands whose timeouts are
+ *	determined using ata_internal_cmd_timeout().
+ *
+ *	LOCKING:
+ *	EH context.
+ */
+void ata_internal_cmd_timed_out(struct ata_device *dev, u8 cmd)
+{
+	struct ata_eh_context *ehc = &dev->link->eh_context;
+	int ent = ata_lookup_timeout_table(cmd);
+	int idx;
+
+	if (ent < 0)
+		return;
+
+	idx = ehc->cmd_timeout_idx[dev->devno][ent];
+	if (ata_eh_cmd_timeout_table[ent].timeouts[idx + 1] != ULONG_MAX)
+		ehc->cmd_timeout_idx[dev->devno][ent]++;
+}
+
+static void ata_ering_record(struct ata_ering *ering, unsigned int eflags,
+			     unsigned int err_mask)
+{
+	struct ata_ering_entry *ent;
+
+	WARN_ON(!err_mask);
+
+	ering->cursor++;
+	ering->cursor %= ATA_ERING_SIZE;
+
+	ent = &ering->ring[ering->cursor];
+	ent->eflags = eflags;
+	ent->err_mask = err_mask;
+	ent->timestamp = get_jiffies_64();
+}
+
+static struct ata_ering_entry *ata_ering_top(struct ata_ering *ering)
+{
+	struct ata_ering_entry *ent = &ering->ring[ering->cursor];
+
+	if (ent->err_mask)
+		return ent;
+	return NULL;
+}
+
+int ata_ering_map(struct ata_ering *ering,
+		  int (*map_fn)(struct ata_ering_entry *, void *),
+		  void *arg)
+{
+	int idx, rc = 0;
+	struct ata_ering_entry *ent;
+
+	idx = ering->cursor;
+	do {
+		ent = &ering->ring[idx];
+		if (!ent->err_mask)
+			break;
+		rc = map_fn(ent, arg);
+		if (rc)
+			break;
+		idx = (idx - 1 + ATA_ERING_SIZE) % ATA_ERING_SIZE;
+	} while (idx != ering->cursor);
+
+	return rc;
+}
+
+static int ata_ering_clear_cb(struct ata_ering_entry *ent, void *void_arg)
+{
+	ent->eflags |= ATA_EFLAG_OLD_ER;
+	return 0;
+}
+
+static void ata_ering_clear(struct ata_ering *ering)
+{
+	ata_ering_map(ering, ata_ering_clear_cb, NULL);
+}
+
+static unsigned int ata_eh_dev_action(struct ata_device *dev)
+{
+	struct ata_eh_context *ehc = &dev->link->eh_context;
+
+	return ehc->i.action | ehc->i.dev_action[dev->devno];
+}
+
+static void ata_eh_clear_action(struct ata_link *link, struct ata_device *dev,
+				struct ata_eh_info *ehi, unsigned int action)
+{
+	struct ata_device *tdev;
+
+	if (!dev) {
+		ehi->action &= ~action;
+		ata_for_each_dev(tdev, link, ALL)
+			ehi->dev_action[tdev->devno] &= ~action;
+	} else {
+		/* doesn't make sense for port-wide EH actions */
+		WARN_ON(!(action & ATA_EH_PERDEV_MASK));
+
+		/* break ehi->action into ehi->dev_action */
+		if (ehi->action & action) {
+			ata_for_each_dev(tdev, link, ALL)
+				ehi->dev_action[tdev->devno] |=
+					ehi->action & action;
+			ehi->action &= ~action;
+		}
+
+		/* turn off the specified per-dev action */
+		ehi->dev_action[dev->devno] &= ~action;
+	}
+}
+
+/**
+ *	ata_eh_acquire - acquire EH ownership
+ *	@ap: ATA port to acquire EH ownership for
+ *
+ *	Acquire EH ownership for @ap.  This is the basic exclusion
+ *	mechanism for ports sharing a host.  Only one port hanging off
+ *	the same host can claim the ownership of EH.
+ *
+ *	LOCKING:
+ *	EH context.
+ */
+void ata_eh_acquire(struct ata_port *ap)
+{
+	mutex_lock(&ap->host->eh_mutex);
+	WARN_ON_ONCE(ap->host->eh_owner);
+	ap->host->eh_owner = current;
+}
+
+/**
+ *	ata_eh_release - release EH ownership
+ *	@ap: ATA port to release EH ownership for
+ *
+ *	Release EH ownership for @ap if the caller.  The caller must
+ *	have acquired EH ownership using ata_eh_acquire() previously.
+ *
+ *	LOCKING:
+ *	EH context.
+ */
+void ata_eh_release(struct ata_port *ap)
+{
+	WARN_ON_ONCE(ap->host->eh_owner != current);
+	ap->host->eh_owner = NULL;
+	mutex_unlock(&ap->host->eh_mutex);
+}
+
+/**
+ *	ata_scsi_timed_out - SCSI layer time out callback
+ *	@cmd: timed out SCSI command
+ *
+ *	Handles SCSI layer timeout.  We race with normal completion of
+ *	the qc for @cmd.  If the qc is already gone, we lose and let
+ *	the scsi command finish (EH_HANDLED).  Otherwise, the qc has
+ *	timed out and EH should be invoked.  Prevent ata_qc_complete()
+ *	from finishing it by setting EH_SCHEDULED and return
+ *	EH_NOT_HANDLED.
+ *
+ *	TODO: kill this function once old EH is gone.
+ *
+ *	LOCKING:
+ *	Called from timer context
+ *
+ *	RETURNS:
+ *	EH_HANDLED or EH_NOT_HANDLED
+ */
+enum blk_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
+{
+	struct Scsi_Host *host = cmd->device->host;
+	struct ata_port *ap = ata_shost_to_port(host);
+	unsigned long flags;
+	struct ata_queued_cmd *qc;
+	enum blk_eh_timer_return ret;
+
+	DPRINTK("ENTER\n");
+
+	if (ap->ops->error_handler) {
+		ret = BLK_EH_NOT_HANDLED;
+		goto out;
+	}
+
+	ret = BLK_EH_HANDLED;
+	spin_lock_irqsave(ap->lock, flags);
+	qc = ata_qc_from_tag(ap, ap->link.active_tag);
+	if (qc) {
+		WARN_ON(qc->scsicmd != cmd);
+		qc->flags |= ATA_QCFLAG_EH_SCHEDULED;
+		qc->err_mask |= AC_ERR_TIMEOUT;
+		ret = BLK_EH_NOT_HANDLED;
+	}
+	spin_unlock_irqrestore(ap->lock, flags);
+
+ out:
+	DPRINTK("EXIT, ret=%d\n", ret);
+	return ret;
+}
+
+static void ata_eh_unload(struct ata_port *ap)
+{
+	struct ata_link *link;
+	struct ata_device *dev;
+	unsigned long flags;
+
+	/* Restore SControl IPM and SPD for the next driver and
+	 * disable attached devices.
+	 */
+	ata_for_each_link(link, ap, PMP_FIRST) {
+		sata_scr_write(link, SCR_CONTROL, link->saved_scontrol & 0xff0);
+		ata_for_each_dev(dev, link, ALL)
+			ata_dev_disable(dev);
+	}
+
+	/* freeze and set UNLOADED */
+	spin_lock_irqsave(ap->lock, flags);
+
+	ata_port_freeze(ap);			/* won't be thawed */
+	ap->pflags &= ~ATA_PFLAG_EH_PENDING;	/* clear pending from freeze */
+	ap->pflags |= ATA_PFLAG_UNLOADED;
+
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *	ata_scsi_error - SCSI layer error handler callback
+ *	@host: SCSI host on which error occurred
+ *
+ *	Handles SCSI-layer-thrown error events.
+ *
+ *	LOCKING:
+ *	Inherited from SCSI layer (none, can sleep)
+ *
+ *	RETURNS:
+ *	Zero.
+ */
+void ata_scsi_error(struct Scsi_Host *host)
+{
+	struct ata_port *ap = ata_shost_to_port(host);
+	unsigned long flags;
+	LIST_HEAD(eh_work_q);
+
+	DPRINTK("ENTER\n");
+
+	spin_lock_irqsave(host->host_lock, flags);
+	list_splice_init(&host->eh_cmd_q, &eh_work_q);
+	spin_unlock_irqrestore(host->host_lock, flags);
+
+	ata_scsi_cmd_error_handler(host, ap, &eh_work_q);
+
+	/* If we timed raced normal completion and there is nothing to
+	   recover nr_timedout == 0 why exactly are we doing error recovery ? */
+	ata_scsi_port_error_handler(host, ap);
+
+	/* finish or retry handled scmd's and clean up */
+	WARN_ON(host->host_failed || !list_empty(&eh_work_q));
+
+	DPRINTK("EXIT\n");
+}
+
+/**
+ * ata_scsi_cmd_error_handler - error callback for a list of commands
+ * @host:	scsi host containing the port
+ * @ap:		ATA port within the host
+ * @eh_work_q:	list of commands to process
+ *
+ * process the given list of commands and return those finished to the
+ * ap->eh_done_q.  This function is the first part of the libata error
+ * handler which processes a given list of failed commands.
+ */
+void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap,
+				struct list_head *eh_work_q)
+{
+	int i;
+	unsigned long flags;
+
+	/* make sure sff pio task is not running */
+	ata_sff_flush_pio_task(ap);
+
+	/* synchronize with host lock and sort out timeouts */
+
+	/* For new EH, all qcs are finished in one of three ways -
+	 * normal completion, error completion, and SCSI timeout.
+	 * Both completions can race against SCSI timeout.  When normal
+	 * completion wins, the qc never reaches EH.  When error
+	 * completion wins, the qc has ATA_QCFLAG_FAILED set.
+	 *
+	 * When SCSI timeout wins, things are a bit more complex.
+	 * Normal or error completion can occur after the timeout but
+	 * before this point.  In such cases, both types of
+	 * completions are honored.  A scmd is determined to have
+	 * timed out iff its associated qc is active and not failed.
+	 */
+	if (ap->ops->error_handler) {
+		struct scsi_cmnd *scmd, *tmp;
+		int nr_timedout = 0;
+
+		spin_lock_irqsave(ap->lock, flags);
+
+		/* This must occur under the ap->lock as we don't want
+		   a polled recovery to race the real interrupt handler
+
+		   The lost_interrupt handler checks for any completed but
+		   non-notified command and completes much like an IRQ handler.
+
+		   We then fall into the error recovery code which will treat
+		   this as if normal completion won the race */
+
+		if (ap->ops->lost_interrupt)
+			ap->ops->lost_interrupt(ap);
+
+		list_for_each_entry_safe(scmd, tmp, eh_work_q, eh_entry) {
+			struct ata_queued_cmd *qc;
+
+			for (i = 0; i < ATA_MAX_QUEUE; i++) {
+				qc = __ata_qc_from_tag(ap, i);
+				if (qc->flags & ATA_QCFLAG_ACTIVE &&
+				    qc->scsicmd == scmd)
+					break;
+			}
+
+			if (i < ATA_MAX_QUEUE) {
+				/* the scmd has an associated qc */
+				if (!(qc->flags & ATA_QCFLAG_FAILED)) {
+					/* which hasn't failed yet, timeout */
+					qc->err_mask |= AC_ERR_TIMEOUT;
+					qc->flags |= ATA_QCFLAG_FAILED;
+					nr_timedout++;
+				}
+			} else {
+				/* Normal completion occurred after
+				 * SCSI timeout but before this point.
+				 * Successfully complete it.
+				 */
+				scmd->retries = scmd->allowed;
+				scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
+			}
+		}
+
+		/* If we have timed out qcs.  They belong to EH from
+		 * this point but the state of the controller is
+		 * unknown.  Freeze the port to make sure the IRQ
+		 * handler doesn't diddle with those qcs.  This must
+		 * be done atomically w.r.t. setting QCFLAG_FAILED.
+		 */
+		if (nr_timedout)
+			__ata_port_freeze(ap);
+
+		spin_unlock_irqrestore(ap->lock, flags);
+
+		/* initialize eh_tries */
+		ap->eh_tries = ATA_EH_MAX_TRIES;
+	} else
+		spin_unlock_wait(ap->lock);
+
+}
+EXPORT_SYMBOL(ata_scsi_cmd_error_handler);
+
+/**
+ * ata_scsi_port_error_handler - recover the port after the commands
+ * @host:	SCSI host containing the port
+ * @ap:		the ATA port
+ *
+ * Handle the recovery of the port @ap after all the commands
+ * have been recovered.
+ */
+void ata_scsi_port_error_handler(struct Scsi_Host *host, struct ata_port *ap)
+{
+	unsigned long flags;
+
+	/* invoke error handler */
+	if (ap->ops->error_handler) {
+		struct ata_link *link;
+
+		/* acquire EH ownership */
+		ata_eh_acquire(ap);
+ repeat:
+		/* kill fast drain timer */
+		del_timer_sync(&ap->fastdrain_timer);
+
+		/* process port resume request */
+		ata_eh_handle_port_resume(ap);
+
+		/* fetch & clear EH info */
+		spin_lock_irqsave(ap->lock, flags);
+
+		ata_for_each_link(link, ap, HOST_FIRST) {
+			struct ata_eh_context *ehc = &link->eh_context;
+			struct ata_device *dev;
+
+			memset(&link->eh_context, 0, sizeof(link->eh_context));
+			link->eh_context.i = link->eh_info;
+			memset(&link->eh_info, 0, sizeof(link->eh_info));
+
+			ata_for_each_dev(dev, link, ENABLED) {
+				int devno = dev->devno;
+
+				ehc->saved_xfer_mode[devno] = dev->xfer_mode;
+				if (ata_ncq_enabled(dev))
+					ehc->saved_ncq_enabled |= 1 << devno;
+			}
+		}
+
+		ap->pflags |= ATA_PFLAG_EH_IN_PROGRESS;
+		ap->pflags &= ~ATA_PFLAG_EH_PENDING;
+		ap->excl_link = NULL;	/* don't maintain exclusion over EH */
+
+		spin_unlock_irqrestore(ap->lock, flags);
+
+		/* invoke EH, skip if unloading or suspended */
+		if (!(ap->pflags & (ATA_PFLAG_UNLOADING | ATA_PFLAG_SUSPENDED)))
+			ap->ops->error_handler(ap);
+		else {
+			/* if unloading, commence suicide */
+			if ((ap->pflags & ATA_PFLAG_UNLOADING) &&
+			    !(ap->pflags & ATA_PFLAG_UNLOADED))
+				ata_eh_unload(ap);
+			ata_eh_finish(ap);
+		}
+
+		/* process port suspend request */
+		ata_eh_handle_port_suspend(ap);
+
+		/* Exception might have happened after ->error_handler
+		 * recovered the port but before this point.  Repeat
+		 * EH in such case.
+		 */
+		spin_lock_irqsave(ap->lock, flags);
+
+		if (ap->pflags & ATA_PFLAG_EH_PENDING) {
+			if (--ap->eh_tries) {
+				spin_unlock_irqrestore(ap->lock, flags);
+				goto repeat;
+			}
+			ata_port_err(ap,
+				     "EH pending after %d tries, giving up\n",
+				     ATA_EH_MAX_TRIES);
+			ap->pflags &= ~ATA_PFLAG_EH_PENDING;
+		}
+
+		/* this run is complete, make sure EH info is clear */
+		ata_for_each_link(link, ap, HOST_FIRST)
+			memset(&link->eh_info, 0, sizeof(link->eh_info));
+
+		/* end eh (clear host_eh_scheduled) while holding
+		 * ap->lock such that if exception occurs after this
+		 * point but before EH completion, SCSI midlayer will
+		 * re-initiate EH.
+		 */
+		ap->ops->end_eh(ap);
+
+		spin_unlock_irqrestore(ap->lock, flags);
+		ata_eh_release(ap);
+	} else {
+		WARN_ON(ata_qc_from_tag(ap, ap->link.active_tag) == NULL);
+		ap->ops->eng_timeout(ap);
+	}
+
+	scsi_eh_flush_done_q(&ap->eh_done_q);
+
+	/* clean up */
+	spin_lock_irqsave(ap->lock, flags);
+
+	if (ap->pflags & ATA_PFLAG_LOADING)
+		ap->pflags &= ~ATA_PFLAG_LOADING;
+	else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG)
+		schedule_delayed_work(&ap->hotplug_task, 0);
+
+	if (ap->pflags & ATA_PFLAG_RECOVERED)
+		ata_port_info(ap, "EH complete\n");
+
+	ap->pflags &= ~(ATA_PFLAG_SCSI_HOTPLUG | ATA_PFLAG_RECOVERED);
+
+	/* tell wait_eh that we're done */
+	ap->pflags &= ~ATA_PFLAG_EH_IN_PROGRESS;
+	wake_up_all(&ap->eh_wait_q);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+EXPORT_SYMBOL_GPL(ata_scsi_port_error_handler);
+
+/**
+ *	ata_port_wait_eh - Wait for the currently pending EH to complete
+ *	@ap: Port to wait EH for
+ *
+ *	Wait until the currently pending EH is complete.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+void ata_port_wait_eh(struct ata_port *ap)
+{
+	unsigned long flags;
+	DEFINE_WAIT(wait);
+
+ retry:
+	spin_lock_irqsave(ap->lock, flags);
+
+	while (ap->pflags & (ATA_PFLAG_EH_PENDING | ATA_PFLAG_EH_IN_PROGRESS)) {
+		prepare_to_wait(&ap->eh_wait_q, &wait, TASK_UNINTERRUPTIBLE);
+		spin_unlock_irqrestore(ap->lock, flags);
+		schedule();
+		spin_lock_irqsave(ap->lock, flags);
+	}
+	finish_wait(&ap->eh_wait_q, &wait);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	/* make sure SCSI EH is complete */
+	if (scsi_host_in_recovery(ap->scsi_host)) {
+		ata_msleep(ap, 10);
+		goto retry;
+	}
+}
+EXPORT_SYMBOL_GPL(ata_port_wait_eh);
+
+static int ata_eh_nr_in_flight(struct ata_port *ap)
+{
+	unsigned int tag;
+	int nr = 0;
+
+	/* count only non-internal commands */
+	for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++)
+		if (ata_qc_from_tag(ap, tag))
+			nr++;
+
+	return nr;
+}
+
+void ata_eh_fastdrain_timerfn(unsigned long arg)
+{
+	struct ata_port *ap = (void *)arg;
+	unsigned long flags;
+	int cnt;
+
+	spin_lock_irqsave(ap->lock, flags);
+
+	cnt = ata_eh_nr_in_flight(ap);
+
+	/* are we done? */
+	if (!cnt)
+		goto out_unlock;
+
+	if (cnt == ap->fastdrain_cnt) {
+		unsigned int tag;
+
+		/* No progress during the last interval, tag all
+		 * in-flight qcs as timed out and freeze the port.
+		 */
+		for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++) {
+			struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
+			if (qc)
+				qc->err_mask |= AC_ERR_TIMEOUT;
+		}
+
+		ata_port_freeze(ap);
+	} else {
+		/* some qcs have finished, give it another chance */
+		ap->fastdrain_cnt = cnt;
+		ap->fastdrain_timer.expires =
+			ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);
+		add_timer(&ap->fastdrain_timer);
+	}
+
+ out_unlock:
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *	ata_eh_set_pending - set ATA_PFLAG_EH_PENDING and activate fast drain
+ *	@ap: target ATA port
+ *	@fastdrain: activate fast drain
+ *
+ *	Set ATA_PFLAG_EH_PENDING and activate fast drain if @fastdrain
+ *	is non-zero and EH wasn't pending before.  Fast drain ensures
+ *	that EH kicks in in timely manner.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+static void ata_eh_set_pending(struct ata_port *ap, int fastdrain)
+{
+	int cnt;
+
+	/* already scheduled? */
+	if (ap->pflags & ATA_PFLAG_EH_PENDING)
+		return;
+
+	ap->pflags |= ATA_PFLAG_EH_PENDING;
+
+	if (!fastdrain)
+		return;
+
+	/* do we have in-flight qcs? */
+	cnt = ata_eh_nr_in_flight(ap);
+	if (!cnt)
+		return;
+
+	/* activate fast drain */
+	ap->fastdrain_cnt = cnt;
+	ap->fastdrain_timer.expires =
+		ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);
+	add_timer(&ap->fastdrain_timer);
+}
+
+/**
+ *	ata_qc_schedule_eh - schedule qc for error handling
+ *	@qc: command to schedule error handling for
+ *
+ *	Schedule error handling for @qc.  EH will kick in as soon as
+ *	other commands are drained.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
+{
+	struct ata_port *ap = qc->ap;
+	struct request_queue *q = qc->scsicmd->device->request_queue;
+	unsigned long flags;
+
+	WARN_ON(!ap->ops->error_handler);
+
+	qc->flags |= ATA_QCFLAG_FAILED;
+	ata_eh_set_pending(ap, 1);
+
+	/* The following will fail if timeout has already expired.
+	 * ata_scsi_error() takes care of such scmds on EH entry.
+	 * Note that ATA_QCFLAG_FAILED is unconditionally set after
+	 * this function completes.
+	 */
+	spin_lock_irqsave(q->queue_lock, flags);
+	blk_abort_request(qc->scsicmd->request);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+/**
+ * ata_std_sched_eh - non-libsas ata_ports issue eh with this common routine
+ * @ap: ATA port to schedule EH for
+ *
+ *	LOCKING: inherited from ata_port_schedule_eh
+ *	spin_lock_irqsave(host lock)
+ */
+void ata_std_sched_eh(struct ata_port *ap)
+{
+	WARN_ON(!ap->ops->error_handler);
+
+	if (ap->pflags & ATA_PFLAG_INITIALIZING)
+		return;
+
+	ata_eh_set_pending(ap, 1);
+	scsi_schedule_eh(ap->scsi_host);
+
+	DPRINTK("port EH scheduled\n");
+}
+EXPORT_SYMBOL_GPL(ata_std_sched_eh);
+
+/**
+ * ata_std_end_eh - non-libsas ata_ports complete eh with this common routine
+ * @ap: ATA port to end EH for
+ *
+ * In the libata object model there is a 1:1 mapping of ata_port to
+ * shost, so host fields can be directly manipulated under ap->lock, in
+ * the libsas case we need to hold a lock at the ha->level to coordinate
+ * these events.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+void ata_std_end_eh(struct ata_port *ap)
+{
+	struct Scsi_Host *host = ap->scsi_host;
+
+	host->host_eh_scheduled = 0;
+}
+EXPORT_SYMBOL(ata_std_end_eh);
+
+
+/**
+ *	ata_port_schedule_eh - schedule error handling without a qc
+ *	@ap: ATA port to schedule EH for
+ *
+ *	Schedule error handling for @ap.  EH will kick in as soon as
+ *	all commands are drained.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+void ata_port_schedule_eh(struct ata_port *ap)
+{
+	/* see: ata_std_sched_eh, unless you know better */
+	ap->ops->sched_eh(ap);
+}
+
+static int ata_do_link_abort(struct ata_port *ap, struct ata_link *link)
+{
+	int tag, nr_aborted = 0;
+
+	WARN_ON(!ap->ops->error_handler);
+
+	/* we're gonna abort all commands, no need for fast drain */
+	ata_eh_set_pending(ap, 0);
+
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
+
+		if (qc && (!link || qc->dev->link == link)) {
+			qc->flags |= ATA_QCFLAG_FAILED;
+			ata_qc_complete(qc);
+			nr_aborted++;
+		}
+	}
+
+	if (!nr_aborted)
+		ata_port_schedule_eh(ap);
+
+	return nr_aborted;
+}
+
+/**
+ *	ata_link_abort - abort all qc's on the link
+ *	@link: ATA link to abort qc's for
+ *
+ *	Abort all active qc's active on @link and schedule EH.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ *
+ *	RETURNS:
+ *	Number of aborted qc's.
+ */
+int ata_link_abort(struct ata_link *link)
+{
+	return ata_do_link_abort(link->ap, link);
+}
+
+/**
+ *	ata_port_abort - abort all qc's on the port
+ *	@ap: ATA port to abort qc's for
+ *
+ *	Abort all active qc's of @ap and schedule EH.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host_set lock)
+ *
+ *	RETURNS:
+ *	Number of aborted qc's.
+ */
+int ata_port_abort(struct ata_port *ap)
+{
+	return ata_do_link_abort(ap, NULL);
+}
+
+/**
+ *	__ata_port_freeze - freeze port
+ *	@ap: ATA port to freeze
+ *
+ *	This function is called when HSM violation or some other
+ *	condition disrupts normal operation of the port.  Frozen port
+ *	is not allowed to perform any operation until the port is
+ *	thawed, which usually follows a successful reset.
+ *
+ *	ap->ops->freeze() callback can be used for freezing the port
+ *	hardware-wise (e.g. mask interrupt and stop DMA engine).  If a
+ *	port cannot be frozen hardware-wise, the interrupt handler
+ *	must ack and clear interrupts unconditionally while the port
+ *	is frozen.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+static void __ata_port_freeze(struct ata_port *ap)
+{
+	WARN_ON(!ap->ops->error_handler);
+
+	if (ap->ops->freeze)
+		ap->ops->freeze(ap);
+
+	ap->pflags |= ATA_PFLAG_FROZEN;
+
+	DPRINTK("ata%u port frozen\n", ap->print_id);
+}
+
+/**
+ *	ata_port_freeze - abort & freeze port
+ *	@ap: ATA port to freeze
+ *
+ *	Abort and freeze @ap.  The freeze operation must be called
+ *	first, because some hardware requires special operations
+ *	before the taskfile registers are accessible.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ *
+ *	RETURNS:
+ *	Number of aborted commands.
+ */
+int ata_port_freeze(struct ata_port *ap)
+{
+	int nr_aborted;
+
+	WARN_ON(!ap->ops->error_handler);
+
+	__ata_port_freeze(ap);
+	nr_aborted = ata_port_abort(ap);
+
+	return nr_aborted;
+}
+
+/**
+ *	sata_async_notification - SATA async notification handler
+ *	@ap: ATA port where async notification is received
+ *
+ *	Handler to be called when async notification via SDB FIS is
+ *	received.  This function schedules EH if necessary.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ *
+ *	RETURNS:
+ *	1 if EH is scheduled, 0 otherwise.
+ */
+int sata_async_notification(struct ata_port *ap)
+{
+	u32 sntf;
+	int rc;
+
+	if (!(ap->flags & ATA_FLAG_AN))
+		return 0;
+
+	rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
+	if (rc == 0)
+		sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);
+
+	if (!sata_pmp_attached(ap) || rc) {
+		/* PMP is not attached or SNTF is not available */
+		if (!sata_pmp_attached(ap)) {
+			/* PMP is not attached.  Check whether ATAPI
+			 * AN is configured.  If so, notify media
+			 * change.
+			 */
+			struct ata_device *dev = ap->link.device;
+
+			if ((dev->class == ATA_DEV_ATAPI) &&
+			    (dev->flags & ATA_DFLAG_AN))
+				ata_scsi_media_change_notify(dev);
+			return 0;
+		} else {
+			/* PMP is attached but SNTF is not available.
+			 * ATAPI async media change notification is
+			 * not used.  The PMP must be reporting PHY
+			 * status change, schedule EH.
+			 */
+			ata_port_schedule_eh(ap);
+			return 1;
+		}
+	} else {
+		/* PMP is attached and SNTF is available */
+		struct ata_link *link;
+
+		/* check and notify ATAPI AN */
+		ata_for_each_link(link, ap, EDGE) {
+			if (!(sntf & (1 << link->pmp)))
+				continue;
+
+			if ((link->device->class == ATA_DEV_ATAPI) &&
+			    (link->device->flags & ATA_DFLAG_AN))
+				ata_scsi_media_change_notify(link->device);
+		}
+
+		/* If PMP is reporting that PHY status of some
+		 * downstream ports has changed, schedule EH.
+		 */
+		if (sntf & (1 << SATA_PMP_CTRL_PORT)) {
+			ata_port_schedule_eh(ap);
+			return 1;
+		}
+
+		return 0;
+	}
+}
+
+/**
+ *	ata_eh_freeze_port - EH helper to freeze port
+ *	@ap: ATA port to freeze
+ *
+ *	Freeze @ap.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_eh_freeze_port(struct ata_port *ap)
+{
+	unsigned long flags;
+
+	if (!ap->ops->error_handler)
+		return;
+
+	spin_lock_irqsave(ap->lock, flags);
+	__ata_port_freeze(ap);
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *	ata_port_thaw_port - EH helper to thaw port
+ *	@ap: ATA port to thaw
+ *
+ *	Thaw frozen port @ap.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_eh_thaw_port(struct ata_port *ap)
+{
+	unsigned long flags;
+
+	if (!ap->ops->error_handler)
+		return;
+
+	spin_lock_irqsave(ap->lock, flags);
+
+	ap->pflags &= ~ATA_PFLAG_FROZEN;
+
+	if (ap->ops->thaw)
+		ap->ops->thaw(ap);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	DPRINTK("ata%u port thawed\n", ap->print_id);
+}
+
+static void ata_eh_scsidone(struct scsi_cmnd *scmd)
+{
+	/* nada */
+}
+
+static void __ata_eh_qc_complete(struct ata_queued_cmd *qc)
+{
+	struct ata_port *ap = qc->ap;
+	struct scsi_cmnd *scmd = qc->scsicmd;
+	unsigned long flags;
+
+	spin_lock_irqsave(ap->lock, flags);
+	qc->scsidone = ata_eh_scsidone;
+	__ata_qc_complete(qc);
+	WARN_ON(ata_tag_valid(qc->tag));
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
+}
+
+/**
+ *	ata_eh_qc_complete - Complete an active ATA command from EH
+ *	@qc: Command to complete
+ *
+ *	Indicate to the mid and upper layers that an ATA command has
+ *	completed.  To be used from EH.
+ */
+void ata_eh_qc_complete(struct ata_queued_cmd *qc)
+{
+	struct scsi_cmnd *scmd = qc->scsicmd;
+	scmd->retries = scmd->allowed;
+	__ata_eh_qc_complete(qc);
+}
+
+/**
+ *	ata_eh_qc_retry - Tell midlayer to retry an ATA command after EH
+ *	@qc: Command to retry
+ *
+ *	Indicate to the mid and upper layers that an ATA command
+ *	should be retried.  To be used from EH.
+ *
+ *	SCSI midlayer limits the number of retries to scmd->allowed.
+ *	scmd->allowed is incremented for commands which get retried
+ *	due to unrelated failures (qc->err_mask is zero).
+ */
+void ata_eh_qc_retry(struct ata_queued_cmd *qc)
+{
+	struct scsi_cmnd *scmd = qc->scsicmd;
+	if (!qc->err_mask)
+		scmd->allowed++;
+	__ata_eh_qc_complete(qc);
+}
+
+/**
+ *	ata_dev_disable - disable ATA device
+ *	@dev: ATA device to disable
+ *
+ *	Disable @dev.
+ *
+ *	Locking:
+ *	EH context.
+ */
+void ata_dev_disable(struct ata_device *dev)
+{
+	if (!ata_dev_enabled(dev))
+		return;
+
+	if (ata_msg_drv(dev->link->ap))
+		ata_dev_warn(dev, "disabled\n");
+	ata_acpi_on_disable(dev);
+	ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO0 | ATA_DNXFER_QUIET);
+	dev->class++;
+
+	/* From now till the next successful probe, ering is used to
+	 * track probe failures.  Clear accumulated device error info.
+	 */
+	ata_ering_clear(&dev->ering);
+}
+
+/**
+ *	ata_eh_detach_dev - detach ATA device
+ *	@dev: ATA device to detach
+ *
+ *	Detach @dev.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_eh_detach_dev(struct ata_device *dev)
+{
+	struct ata_link *link = dev->link;
+	struct ata_port *ap = link->ap;
+	struct ata_eh_context *ehc = &link->eh_context;
+	unsigned long flags;
+
+	ata_dev_disable(dev);
+
+	spin_lock_irqsave(ap->lock, flags);
+
+	dev->flags &= ~ATA_DFLAG_DETACH;
+
+	if (ata_scsi_offline_dev(dev)) {
+		dev->flags |= ATA_DFLAG_DETACHED;
+		ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
+	}
+
+	/* clear per-dev EH info */
+	ata_eh_clear_action(link, dev, &link->eh_info, ATA_EH_PERDEV_MASK);
+	ata_eh_clear_action(link, dev, &link->eh_context.i, ATA_EH_PERDEV_MASK);
+	ehc->saved_xfer_mode[dev->devno] = 0;
+	ehc->saved_ncq_enabled &= ~(1 << dev->devno);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *	ata_eh_about_to_do - about to perform eh_action
+ *	@link: target ATA link
+ *	@dev: target ATA dev for per-dev action (can be NULL)
+ *	@action: action about to be performed
+ *
+ *	Called just before performing EH actions to clear related bits
+ *	in @link->eh_info such that eh actions are not unnecessarily
+ *	repeated.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
+			unsigned int action)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_eh_info *ehi = &link->eh_info;
+	struct ata_eh_context *ehc = &link->eh_context;
+	unsigned long flags;
+
+	spin_lock_irqsave(ap->lock, flags);
+
+	ata_eh_clear_action(link, dev, ehi, action);
+
+	/* About to take EH action, set RECOVERED.  Ignore actions on
+	 * slave links as master will do them again.
+	 */
+	if (!(ehc->i.flags & ATA_EHI_QUIET) && link != ap->slave_link)
+		ap->pflags |= ATA_PFLAG_RECOVERED;
+
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *	ata_eh_done - EH action complete
+*	@ap: target ATA port
+ *	@dev: target ATA dev for per-dev action (can be NULL)
+ *	@action: action just completed
+ *
+ *	Called right after performing EH actions to clear related bits
+ *	in @link->eh_context.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_eh_done(struct ata_link *link, struct ata_device *dev,
+		 unsigned int action)
+{
+	struct ata_eh_context *ehc = &link->eh_context;
+
+	ata_eh_clear_action(link, dev, &ehc->i, action);
+}
+
+/**
+ *	ata_err_string - convert err_mask to descriptive string
+ *	@err_mask: error mask to convert to string
+ *
+ *	Convert @err_mask to descriptive string.  Errors are
+ *	prioritized according to severity and only the most severe
+ *	error is reported.
+ *
+ *	LOCKING:
+ *	None.
+ *
+ *	RETURNS:
+ *	Descriptive string for @err_mask
+ */
+static const char *ata_err_string(unsigned int err_mask)
+{
+	if (err_mask & AC_ERR_HOST_BUS)
+		return "host bus error";
+	if (err_mask & AC_ERR_ATA_BUS)
+		return "ATA bus error";
+	if (err_mask & AC_ERR_TIMEOUT)
+		return "timeout";
+	if (err_mask & AC_ERR_HSM)
+		return "HSM violation";
+	if (err_mask & AC_ERR_SYSTEM)
+		return "internal error";
+	if (err_mask & AC_ERR_MEDIA)
+		return "media error";
+	if (err_mask & AC_ERR_INVALID)
+		return "invalid argument";
+	if (err_mask & AC_ERR_DEV)
+		return "device error";
+	return "unknown error";
+}
+
+/**
+ *	ata_read_log_page - read a specific log page
+ *	@dev: target device
+ *	@log: log to read
+ *	@page: page to read
+ *	@buf: buffer to store read page
+ *	@sectors: number of sectors to read
+ *
+ *	Read log page using READ_LOG_EXT command.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, AC_ERR_* mask otherwise.
+ */
+unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
+			       u8 page, void *buf, unsigned int sectors)
+{
+	struct ata_taskfile tf;
+	unsigned int err_mask;
+	bool dma = false;
+
+	DPRINTK("read log page - log 0x%x, page 0x%x\n", log, page);
+
+retry:
+	ata_tf_init(dev, &tf);
+	if (dev->dma_mode && ata_id_has_read_log_dma_ext(dev->id) &&
+	    !(dev->horkage & ATA_HORKAGE_NO_NCQ_LOG)) {
+		tf.command = ATA_CMD_READ_LOG_DMA_EXT;
+		tf.protocol = ATA_PROT_DMA;
+		dma = true;
+	} else {
+		tf.command = ATA_CMD_READ_LOG_EXT;
+		tf.protocol = ATA_PROT_PIO;
+		dma = false;
+	}
+	tf.lbal = log;
+	tf.lbam = page;
+	tf.nsect = sectors;
+	tf.hob_nsect = sectors >> 8;
+	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_LBA48 | ATA_TFLAG_DEVICE;
+
+	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,
+				     buf, sectors * ATA_SECT_SIZE, 0);
+
+	if (err_mask && dma) {
+		dev->horkage |= ATA_HORKAGE_NO_NCQ_LOG;
+		ata_dev_warn(dev, "READ LOG DMA EXT failed, trying unqueued\n");
+		goto retry;
+	}
+
+	DPRINTK("EXIT, err_mask=%x\n", err_mask);
+	return err_mask;
+}
+
+/**
+ *	ata_eh_read_log_10h - Read log page 10h for NCQ error details
+ *	@dev: Device to read log page 10h from
+ *	@tag: Resulting tag of the failed command
+ *	@tf: Resulting taskfile registers of the failed command
+ *
+ *	Read log page 10h to obtain NCQ error details and clear error
+ *	condition.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno otherwise.
+ */
+static int ata_eh_read_log_10h(struct ata_device *dev,
+			       int *tag, struct ata_taskfile *tf)
+{
+	u8 *buf = dev->link->ap->sector_buf;
+	unsigned int err_mask;
+	u8 csum;
+	int i;
+
+	err_mask = ata_read_log_page(dev, ATA_LOG_SATA_NCQ, 0, buf, 1);
+	if (err_mask)
+		return -EIO;
+
+	csum = 0;
+	for (i = 0; i < ATA_SECT_SIZE; i++)
+		csum += buf[i];
+	if (csum)
+		ata_dev_warn(dev, "invalid checksum 0x%x on log page 10h\n",
+			     csum);
+
+	if (buf[0] & 0x80)
+		return -ENOENT;
+
+	*tag = buf[0] & 0x1f;
+
+	tf->command = buf[2];
+	tf->feature = buf[3];
+	tf->lbal = buf[4];
+	tf->lbam = buf[5];
+	tf->lbah = buf[6];
+	tf->device = buf[7];
+	tf->hob_lbal = buf[8];
+	tf->hob_lbam = buf[9];
+	tf->hob_lbah = buf[10];
+	tf->nsect = buf[12];
+	tf->hob_nsect = buf[13];
+	if (ata_id_has_ncq_autosense(dev->id))
+		tf->auxiliary = buf[14] << 16 | buf[15] << 8 | buf[16];
+
+	return 0;
+}
+
+/**
+ *	atapi_eh_tur - perform ATAPI TEST_UNIT_READY
+ *	@dev: target ATAPI device
+ *	@r_sense_key: out parameter for sense_key
+ *
+ *	Perform ATAPI TEST_UNIT_READY.
+ *
+ *	LOCKING:
+ *	EH context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, AC_ERR_* mask on failure.
+ */
+unsigned int atapi_eh_tur(struct ata_device *dev, u8 *r_sense_key)
+{
+	u8 cdb[ATAPI_CDB_LEN] = { TEST_UNIT_READY, 0, 0, 0, 0, 0 };
+	struct ata_taskfile tf;
+	unsigned int err_mask;
+
+	ata_tf_init(dev, &tf);
+
+	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf.command = ATA_CMD_PACKET;
+	tf.protocol = ATAPI_PROT_NODATA;
+
+	err_mask = ata_exec_internal(dev, &tf, cdb, DMA_NONE, NULL, 0, 0);
+	if (err_mask == AC_ERR_DEV)
+		*r_sense_key = tf.feature >> 4;
+	return err_mask;
+}
+
+/**
+ *	ata_eh_request_sense - perform REQUEST_SENSE_DATA_EXT
+ *	@dev: device to perform REQUEST_SENSE_SENSE_DATA_EXT to
+ *	@sense_buf: result sense data buffer (SCSI_SENSE_BUFFERSIZE bytes long)
+ *	@dfl_sense_key: default sense key to use
+ *
+ *	Perform REQUEST_SENSE_DATA_EXT after the device reported CHECK
+ *	SENSE.  This function is EH helper.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	encoded sense data on success, 0 on failure or if sense data
+ *	is not available.
+ */
+static u32 ata_eh_request_sense(struct ata_queued_cmd *qc,
+				struct scsi_cmnd *cmd)
+{
+	struct ata_device *dev = qc->dev;
+	struct ata_taskfile tf;
+	unsigned int err_mask;
+
+	if (!cmd)
+		return 0;
+
+	DPRINTK("ATA request sense\n");
+	ata_dev_warn(dev, "request sense\n");
+	if (!ata_id_sense_reporting_enabled(dev->id)) {
+		ata_dev_warn(qc->dev, "sense data reporting disabled\n");
+		return 0;
+	}
+	ata_tf_init(dev, &tf);
+
+	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf.flags |= ATA_TFLAG_LBA | ATA_TFLAG_LBA48;
+	tf.command = ATA_CMD_REQ_SENSE_DATA;
+	tf.protocol = ATA_PROT_NODATA;
+
+	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
+	/*
+	 * ACS-4 states:
+	 * The device may set the SENSE DATA AVAILABLE bit to one in the
+	 * STATUS field and clear the ERROR bit to zero in the STATUS field
+	 * to indicate that the command returned completion without an error
+	 * and the sense data described in table 306 is available.
+	 *
+	 * IOW the 'ATA_SENSE' bit might not be set even though valid
+	 * sense data is available.
+	 * So check for both.
+	 */
+	if ((tf.command & ATA_SENSE) ||
+		tf.lbah != 0 || tf.lbam != 0 || tf.lbal != 0) {
+		ata_scsi_set_sense(cmd, tf.lbah, tf.lbam, tf.lbal);
+		qc->flags |= ATA_QCFLAG_SENSE_VALID;
+		ata_dev_warn(dev, "sense data %02x/%02x/%02x\n",
+			     tf.lbah, tf.lbam, tf.lbal);
+	} else {
+		ata_dev_warn(dev, "request sense failed stat %02x emask %x\n",
+			     tf.command, err_mask);
+	}
+	return err_mask;
+}
+
+/**
+ *	atapi_eh_request_sense - perform ATAPI REQUEST_SENSE
+ *	@dev: device to perform REQUEST_SENSE to
+ *	@sense_buf: result sense data buffer (SCSI_SENSE_BUFFERSIZE bytes long)
+ *	@dfl_sense_key: default sense key to use
+ *
+ *	Perform ATAPI REQUEST_SENSE after the device reported CHECK
+ *	SENSE.  This function is EH helper.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, AC_ERR_* mask on failure
+ */
+unsigned int atapi_eh_request_sense(struct ata_device *dev,
+					   u8 *sense_buf, u8 dfl_sense_key)
+{
+	u8 cdb[ATAPI_CDB_LEN] =
+		{ REQUEST_SENSE, 0, 0, 0, SCSI_SENSE_BUFFERSIZE, 0 };
+	struct ata_port *ap = dev->link->ap;
+	struct ata_taskfile tf;
+
+	DPRINTK("ATAPI request sense\n");
+
+	memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);
+
+	/* initialize sense_buf with the error register,
+	 * for the case where they are -not- overwritten
+	 */
+	sense_buf[0] = 0x70;
+	sense_buf[2] = dfl_sense_key;
+
+	/* some devices time out if garbage left in tf */
+	ata_tf_init(dev, &tf);
+
+	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf.command = ATA_CMD_PACKET;
+
+	/* is it pointless to prefer PIO for "safety reasons"? */
+	if (ap->flags & ATA_FLAG_PIO_DMA) {
+		tf.protocol = ATAPI_PROT_DMA;
+		tf.feature |= ATAPI_PKT_DMA;
+	} else {
+		tf.protocol = ATAPI_PROT_PIO;
+		tf.lbam = SCSI_SENSE_BUFFERSIZE;
+		tf.lbah = 0;
+	}
+
+	return ata_exec_internal(dev, &tf, cdb, DMA_FROM_DEVICE,
+				 sense_buf, SCSI_SENSE_BUFFERSIZE, 0);
+}
+
+/**
+ *	ata_eh_analyze_serror - analyze SError for a failed port
+ *	@link: ATA link to analyze SError for
+ *
+ *	Analyze SError if available and further determine cause of
+ *	failure.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void ata_eh_analyze_serror(struct ata_link *link)
+{
+	struct ata_eh_context *ehc = &link->eh_context;
+	u32 serror = ehc->i.serror;
+	unsigned int err_mask = 0, action = 0;
+	u32 hotplug_mask;
+
+	if (serror & (SERR_PERSISTENT | SERR_DATA)) {
+		err_mask |= AC_ERR_ATA_BUS;
+		action |= ATA_EH_RESET;
+	}
+	if (serror & SERR_PROTOCOL) {
+		err_mask |= AC_ERR_HSM;
+		action |= ATA_EH_RESET;
+	}
+	if (serror & SERR_INTERNAL) {
+		err_mask |= AC_ERR_SYSTEM;
+		action |= ATA_EH_RESET;
+	}
+
+	/* Determine whether a hotplug event has occurred.  Both
+	 * SError.N/X are considered hotplug events for enabled or
+	 * host links.  For disabled PMP links, only N bit is
+	 * considered as X bit is left at 1 for link plugging.
+	 */
+	if (link->lpm_policy > ATA_LPM_MAX_POWER)
+		hotplug_mask = 0;	/* hotplug doesn't work w/ LPM */
+	else if (!(link->flags & ATA_LFLAG_DISABLED) || ata_is_host_link(link))
+		hotplug_mask = SERR_PHYRDY_CHG | SERR_DEV_XCHG;
+	else
+		hotplug_mask = SERR_PHYRDY_CHG;
+
+	if (serror & hotplug_mask)
+		ata_ehi_hotplugged(&ehc->i);
+
+	ehc->i.err_mask |= err_mask;
+	ehc->i.action |= action;
+}
+
+/**
+ *	ata_eh_analyze_ncq_error - analyze NCQ error
+ *	@link: ATA link to analyze NCQ error for
+ *
+ *	Read log page 10h, determine the offending qc and acquire
+ *	error status TF.  For NCQ device errors, all LLDDs have to do
+ *	is setting AC_ERR_DEV in ehi->err_mask.  This function takes
+ *	care of the rest.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+void ata_eh_analyze_ncq_error(struct ata_link *link)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_eh_context *ehc = &link->eh_context;
+	struct ata_device *dev = link->device;
+	struct ata_queued_cmd *qc;
+	struct ata_taskfile tf;
+	int tag, rc;
+
+	/* if frozen, we can't do much */
+	if (ap->pflags & ATA_PFLAG_FROZEN)
+		return;
+
+	/* is it NCQ device error? */
+	if (!link->sactive || !(ehc->i.err_mask & AC_ERR_DEV))
+		return;
+
+	/* has LLDD analyzed already? */
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		qc = __ata_qc_from_tag(ap, tag);
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED))
+			continue;
+
+		if (qc->err_mask)
+			return;
+	}
+
+	/* okay, this error is ours */
+	memset(&tf, 0, sizeof(tf));
+	rc = ata_eh_read_log_10h(dev, &tag, &tf);
+	if (rc) {
+		ata_link_err(link, "failed to read log page 10h (errno=%d)\n",
+			     rc);
+		return;
+	}
+
+	if (!(link->sactive & (1 << tag))) {
+		ata_link_err(link, "log page 10h reported inactive tag %d\n",
+			     tag);
+		return;
+	}
+
+	/* we've got the perpetrator, condemn it */
+	qc = __ata_qc_from_tag(ap, tag);
+	memcpy(&qc->result_tf, &tf, sizeof(tf));
+	qc->result_tf.flags = ATA_TFLAG_ISADDR | ATA_TFLAG_LBA | ATA_TFLAG_LBA48;
+	qc->err_mask |= AC_ERR_DEV | AC_ERR_NCQ;
+	if (qc->result_tf.auxiliary) {
+		char sense_key, asc, ascq;
+
+		sense_key = (qc->result_tf.auxiliary >> 16) & 0xff;
+		asc = (qc->result_tf.auxiliary >> 8) & 0xff;
+		ascq = qc->result_tf.auxiliary & 0xff;
+		ata_dev_dbg(dev, "NCQ Autosense %02x/%02x/%02x\n",
+			    sense_key, asc, ascq);
+		ata_scsi_set_sense(qc->scsicmd, sense_key, asc, ascq);
+		ata_scsi_set_sense_information(qc->scsicmd, &qc->result_tf);
+		qc->flags |= ATA_QCFLAG_SENSE_VALID;
+	}
+
+	ehc->i.err_mask &= ~AC_ERR_DEV;
+}
+
+/**
+ *	ata_eh_analyze_tf - analyze taskfile of a failed qc
+ *	@qc: qc to analyze
+ *	@tf: Taskfile registers to analyze
+ *
+ *	Analyze taskfile of @qc and further determine cause of
+ *	failure.  This function also requests ATAPI sense data if
+ *	available.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	Determined recovery action
+ */
+static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
+				      const struct ata_taskfile *tf)
+{
+	unsigned int tmp, action = 0;
+	u8 stat = tf->command, err = tf->feature;
+
+	if ((stat & (ATA_BUSY | ATA_DRQ | ATA_DRDY)) != ATA_DRDY) {
+		qc->err_mask |= AC_ERR_HSM;
+		return ATA_EH_RESET;
+	}
+
+	/*
+	 * Sense data reporting does not work if the
+	 * device fault bit is set.
+	 */
+	if ((stat & ATA_SENSE) && !(stat & ATA_DF) &&
+	    !(qc->flags & ATA_QCFLAG_SENSE_VALID)) {
+		if (!(qc->ap->pflags & ATA_PFLAG_FROZEN)) {
+			tmp = ata_eh_request_sense(qc, qc->scsicmd);
+			if (tmp)
+				qc->err_mask |= tmp;
+			else
+				ata_scsi_set_sense_information(qc->scsicmd, tf);
+		} else {
+			ata_dev_warn(qc->dev, "sense data available but port frozen\n");
+		}
+	}
+
+	/* Set by NCQ autosense or request sense above */
+	if (qc->flags & ATA_QCFLAG_SENSE_VALID)
+		return 0;
+
+	if (stat & (ATA_ERR | ATA_DF))
+		qc->err_mask |= AC_ERR_DEV;
+	else
+		return 0;
+
+	switch (qc->dev->class) {
+	case ATA_DEV_ATA:
+	case ATA_DEV_ZAC:
+		if (err & ATA_ICRC)
+			qc->err_mask |= AC_ERR_ATA_BUS;
+		if (err & (ATA_UNC | ATA_AMNF))
+			qc->err_mask |= AC_ERR_MEDIA;
+		if (err & ATA_IDNF)
+			qc->err_mask |= AC_ERR_INVALID;
+		break;
+
+	case ATA_DEV_ATAPI:
+		if (!(qc->ap->pflags & ATA_PFLAG_FROZEN)) {
+			tmp = atapi_eh_request_sense(qc->dev,
+						qc->scsicmd->sense_buffer,
+						qc->result_tf.feature >> 4);
+			if (!tmp) {
+				/* ATA_QCFLAG_SENSE_VALID is used to
+				 * tell atapi_qc_complete() that sense
+				 * data is already valid.
+				 *
+				 * TODO: interpret sense data and set
+				 * appropriate err_mask.
+				 */
+				qc->flags |= ATA_QCFLAG_SENSE_VALID;
+			} else
+				qc->err_mask |= tmp;
+		}
+	}
+
+	if (qc->err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT | AC_ERR_ATA_BUS))
+		action |= ATA_EH_RESET;
+
+	return action;
+}
+
+static int ata_eh_categorize_error(unsigned int eflags, unsigned int err_mask,
+				   int *xfer_ok)
+{
+	int base = 0;
+
+	if (!(eflags & ATA_EFLAG_DUBIOUS_XFER))
+		*xfer_ok = 1;
+
+	if (!*xfer_ok)
+		base = ATA_ECAT_DUBIOUS_NONE;
+
+	if (err_mask & AC_ERR_ATA_BUS)
+		return base + ATA_ECAT_ATA_BUS;
+
+	if (err_mask & AC_ERR_TIMEOUT)
+		return base + ATA_ECAT_TOUT_HSM;
+
+	if (eflags & ATA_EFLAG_IS_IO) {
+		if (err_mask & AC_ERR_HSM)
+			return base + ATA_ECAT_TOUT_HSM;
+		if ((err_mask &
+		     (AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)
+			return base + ATA_ECAT_UNK_DEV;
+	}
+
+	return 0;
+}
+
+struct speed_down_verdict_arg {
+	u64 since;
+	int xfer_ok;
+	int nr_errors[ATA_ECAT_NR];
+};
+
+static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)
+{
+	struct speed_down_verdict_arg *arg = void_arg;
+	int cat;
+
+	if ((ent->eflags & ATA_EFLAG_OLD_ER) || (ent->timestamp < arg->since))
+		return -1;
+
+	cat = ata_eh_categorize_error(ent->eflags, ent->err_mask,
+				      &arg->xfer_ok);
+	arg->nr_errors[cat]++;
+
+	return 0;
+}
+
+/**
+ *	ata_eh_speed_down_verdict - Determine speed down verdict
+ *	@dev: Device of interest
+ *
+ *	This function examines error ring of @dev and determines
+ *	whether NCQ needs to be turned off, transfer speed should be
+ *	stepped down, or falling back to PIO is necessary.
+ *
+ *	ECAT_ATA_BUS	: ATA_BUS error for any command
+ *
+ *	ECAT_TOUT_HSM	: TIMEOUT for any command or HSM violation for
+ *			  IO commands
+ *
+ *	ECAT_UNK_DEV	: Unknown DEV error for IO commands
+ *
+ *	ECAT_DUBIOUS_*	: Identical to above three but occurred while
+ *			  data transfer hasn't been verified.
+ *
+ *	Verdicts are
+ *
+ *	NCQ_OFF		: Turn off NCQ.
+ *
+ *	SPEED_DOWN	: Speed down transfer speed but don't fall back
+ *			  to PIO.
+ *
+ *	FALLBACK_TO_PIO	: Fall back to PIO.
+ *
+ *	Even if multiple verdicts are returned, only one action is
+ *	taken per error.  An action triggered by non-DUBIOUS errors
+ *	clears ering, while one triggered by DUBIOUS_* errors doesn't.
+ *	This is to expedite speed down decisions right after device is
+ *	initially configured.
+ *
+ *	The followings are speed down rules.  #1 and #2 deal with
+ *	DUBIOUS errors.
+ *
+ *	1. If more than one DUBIOUS_ATA_BUS or DUBIOUS_TOUT_HSM errors
+ *	   occurred during last 5 mins, SPEED_DOWN and FALLBACK_TO_PIO.
+ *
+ *	2. If more than one DUBIOUS_TOUT_HSM or DUBIOUS_UNK_DEV errors
+ *	   occurred during last 5 mins, NCQ_OFF.
+ *
+ *	3. If more than 8 ATA_BUS, TOUT_HSM or UNK_DEV errors
+ *	   occurred during last 5 mins, FALLBACK_TO_PIO
+ *
+ *	4. If more than 3 TOUT_HSM or UNK_DEV errors occurred
+ *	   during last 10 mins, NCQ_OFF.
+ *
+ *	5. If more than 3 ATA_BUS or TOUT_HSM errors, or more than 6
+ *	   UNK_DEV errors occurred during last 10 mins, SPEED_DOWN.
+ *
+ *	LOCKING:
+ *	Inherited from caller.
+ *
+ *	RETURNS:
+ *	OR of ATA_EH_SPDN_* flags.
+ */
+static unsigned int ata_eh_speed_down_verdict(struct ata_device *dev)
+{
+	const u64 j5mins = 5LLU * 60 * HZ, j10mins = 10LLU * 60 * HZ;
+	u64 j64 = get_jiffies_64();
+	struct speed_down_verdict_arg arg;
+	unsigned int verdict = 0;
+
+	/* scan past 5 mins of error history */
+	memset(&arg, 0, sizeof(arg));
+	arg.since = j64 - min(j64, j5mins);
+	ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);
+
+	if (arg.nr_errors[ATA_ECAT_DUBIOUS_ATA_BUS] +
+	    arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] > 1)
+		verdict |= ATA_EH_SPDN_SPEED_DOWN |
+			ATA_EH_SPDN_FALLBACK_TO_PIO | ATA_EH_SPDN_KEEP_ERRORS;
+
+	if (arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] +
+	    arg.nr_errors[ATA_ECAT_DUBIOUS_UNK_DEV] > 1)
+		verdict |= ATA_EH_SPDN_NCQ_OFF | ATA_EH_SPDN_KEEP_ERRORS;
+
+	if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
+	    arg.nr_errors[ATA_ECAT_TOUT_HSM] +
+	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)
+		verdict |= ATA_EH_SPDN_FALLBACK_TO_PIO;
+
+	/* scan past 10 mins of error history */
+	memset(&arg, 0, sizeof(arg));
+	arg.since = j64 - min(j64, j10mins);
+	ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);
+
+	if (arg.nr_errors[ATA_ECAT_TOUT_HSM] +
+	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 3)
+		verdict |= ATA_EH_SPDN_NCQ_OFF;
+
+	if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
+	    arg.nr_errors[ATA_ECAT_TOUT_HSM] > 3 ||
+	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)
+		verdict |= ATA_EH_SPDN_SPEED_DOWN;
+
+	return verdict;
+}
+
+/**
+ *	ata_eh_speed_down - record error and speed down if necessary
+ *	@dev: Failed device
+ *	@eflags: mask of ATA_EFLAG_* flags
+ *	@err_mask: err_mask of the error
+ *
+ *	Record error and examine error history to determine whether
+ *	adjusting transmission speed is necessary.  It also sets
+ *	transmission limits appropriately if such adjustment is
+ *	necessary.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	Determined recovery action.
+ */
+static unsigned int ata_eh_speed_down(struct ata_device *dev,
+				unsigned int eflags, unsigned int err_mask)
+{
+	struct ata_link *link = ata_dev_phys_link(dev);
+	int xfer_ok = 0;
+	unsigned int verdict;
+	unsigned int action = 0;
+
+	/* don't bother if Cat-0 error */
+	if (ata_eh_categorize_error(eflags, err_mask, &xfer_ok) == 0)
+		return 0;
+
+	/* record error and determine whether speed down is necessary */
+	ata_ering_record(&dev->ering, eflags, err_mask);
+	verdict = ata_eh_speed_down_verdict(dev);
+
+	/* turn off NCQ? */
+	if ((verdict & ATA_EH_SPDN_NCQ_OFF) &&
+	    (dev->flags & (ATA_DFLAG_PIO | ATA_DFLAG_NCQ |
+			   ATA_DFLAG_NCQ_OFF)) == ATA_DFLAG_NCQ) {
+		dev->flags |= ATA_DFLAG_NCQ_OFF;
+		ata_dev_warn(dev, "NCQ disabled due to excessive errors\n");
+		goto done;
+	}
+
+	/* speed down? */
+	if (verdict & ATA_EH_SPDN_SPEED_DOWN) {
+		/* speed down SATA link speed if possible */
+		if (sata_down_spd_limit(link, 0) == 0) {
+			action |= ATA_EH_RESET;
+			goto done;
+		}
+
+		/* lower transfer mode */
+		if (dev->spdn_cnt < 2) {
+			static const int dma_dnxfer_sel[] =
+				{ ATA_DNXFER_DMA, ATA_DNXFER_40C };
+			static const int pio_dnxfer_sel[] =
+				{ ATA_DNXFER_PIO, ATA_DNXFER_FORCE_PIO0 };
+			int sel;
+
+			if (dev->xfer_shift != ATA_SHIFT_PIO)
+				sel = dma_dnxfer_sel[dev->spdn_cnt];
+			else
+				sel = pio_dnxfer_sel[dev->spdn_cnt];
+
+			dev->spdn_cnt++;
+
+			if (ata_down_xfermask_limit(dev, sel) == 0) {
+				action |= ATA_EH_RESET;
+				goto done;
+			}
+		}
+	}
+
+	/* Fall back to PIO?  Slowing down to PIO is meaningless for
+	 * SATA ATA devices.  Consider it only for PATA and SATAPI.
+	 */
+	if ((verdict & ATA_EH_SPDN_FALLBACK_TO_PIO) && (dev->spdn_cnt >= 2) &&
+	    (link->ap->cbl != ATA_CBL_SATA || dev->class == ATA_DEV_ATAPI) &&
+	    (dev->xfer_shift != ATA_SHIFT_PIO)) {
+		if (ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO) == 0) {
+			dev->spdn_cnt = 0;
+			action |= ATA_EH_RESET;
+			goto done;
+		}
+	}
+
+	return 0;
+ done:
+	/* device has been slowed down, blow error history */
+	if (!(verdict & ATA_EH_SPDN_KEEP_ERRORS))
+		ata_ering_clear(&dev->ering);
+	return action;
+}
+
+/**
+ *	ata_eh_worth_retry - analyze error and decide whether to retry
+ *	@qc: qc to possibly retry
+ *
+ *	Look at the cause of the error and decide if a retry
+ * 	might be useful or not.  We don't want to retry media errors
+ *	because the drive itself has probably already taken 10-30 seconds
+ *	doing its own internal retries before reporting the failure.
+ */
+static inline int ata_eh_worth_retry(struct ata_queued_cmd *qc)
+{
+	if (qc->err_mask & AC_ERR_MEDIA)
+		return 0;	/* don't retry media errors */
+	if (qc->flags & ATA_QCFLAG_IO)
+		return 1;	/* otherwise retry anything from fs stack */
+	if (qc->err_mask & AC_ERR_INVALID)
+		return 0;	/* don't retry these */
+	return qc->err_mask != AC_ERR_DEV;  /* retry if not dev error */
+}
+
+/**
+ *	ata_eh_link_autopsy - analyze error and determine recovery action
+ *	@link: host link to perform autopsy on
+ *
+ *	Analyze why @link failed and determine which recovery actions
+ *	are needed.  This function also sets more detailed AC_ERR_*
+ *	values and fills sense data for ATAPI CHECK SENSE.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+static void ata_eh_link_autopsy(struct ata_link *link)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_eh_context *ehc = &link->eh_context;
+	struct ata_device *dev;
+	unsigned int all_err_mask = 0, eflags = 0;
+	int tag;
+	u32 serror;
+	int rc;
+
+	DPRINTK("ENTER\n");
+
+	if (ehc->i.flags & ATA_EHI_NO_AUTOPSY)
+		return;
+
+	/* obtain and analyze SError */
+	rc = sata_scr_read(link, SCR_ERROR, &serror);
+	if (rc == 0) {
+		ehc->i.serror |= serror;
+		ata_eh_analyze_serror(link);
+	} else if (rc != -EOPNOTSUPP) {
+		/* SError read failed, force reset and probing */
+		ehc->i.probe_mask |= ATA_ALL_DEVICES;
+		ehc->i.action |= ATA_EH_RESET;
+		ehc->i.err_mask |= AC_ERR_OTHER;
+	}
+
+	/* analyze NCQ failure */
+	ata_eh_analyze_ncq_error(link);
+
+	/* any real error trumps AC_ERR_OTHER */
+	if (ehc->i.err_mask & ~AC_ERR_OTHER)
+		ehc->i.err_mask &= ~AC_ERR_OTHER;
+
+	all_err_mask |= ehc->i.err_mask;
+
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED) ||
+		    ata_dev_phys_link(qc->dev) != link)
+			continue;
+
+		/* inherit upper level err_mask */
+		qc->err_mask |= ehc->i.err_mask;
+
+		/* analyze TF */
+		ehc->i.action |= ata_eh_analyze_tf(qc, &qc->result_tf);
+
+		/* DEV errors are probably spurious in case of ATA_BUS error */
+		if (qc->err_mask & AC_ERR_ATA_BUS)
+			qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_MEDIA |
+					  AC_ERR_INVALID);
+
+		/* any real error trumps unknown error */
+		if (qc->err_mask & ~AC_ERR_OTHER)
+			qc->err_mask &= ~AC_ERR_OTHER;
+
+		/* SENSE_VALID trumps dev/unknown error and revalidation */
+		if (qc->flags & ATA_QCFLAG_SENSE_VALID)
+			qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_OTHER);
+
+		/* determine whether the command is worth retrying */
+		if (ata_eh_worth_retry(qc))
+			qc->flags |= ATA_QCFLAG_RETRY;
+
+		/* accumulate error info */
+		ehc->i.dev = qc->dev;
+		all_err_mask |= qc->err_mask;
+		if (qc->flags & ATA_QCFLAG_IO)
+			eflags |= ATA_EFLAG_IS_IO;
+		trace_ata_eh_link_autopsy_qc(qc);
+	}
+
+	/* enforce default EH actions */
+	if (ap->pflags & ATA_PFLAG_FROZEN ||
+	    all_err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT))
+		ehc->i.action |= ATA_EH_RESET;
+	else if (((eflags & ATA_EFLAG_IS_IO) && all_err_mask) ||
+		 (!(eflags & ATA_EFLAG_IS_IO) && (all_err_mask & ~AC_ERR_DEV)))
+		ehc->i.action |= ATA_EH_REVALIDATE;
+
+	/* If we have offending qcs and the associated failed device,
+	 * perform per-dev EH action only on the offending device.
+	 */
+	if (ehc->i.dev) {
+		ehc->i.dev_action[ehc->i.dev->devno] |=
+			ehc->i.action & ATA_EH_PERDEV_MASK;
+		ehc->i.action &= ~ATA_EH_PERDEV_MASK;
+	}
+
+	/* propagate timeout to host link */
+	if ((all_err_mask & AC_ERR_TIMEOUT) && !ata_is_host_link(link))
+		ap->link.eh_context.i.err_mask |= AC_ERR_TIMEOUT;
+
+	/* record error and consider speeding down */
+	dev = ehc->i.dev;
+	if (!dev && ((ata_link_max_devices(link) == 1 &&
+		      ata_dev_enabled(link->device))))
+	    dev = link->device;
+
+	if (dev) {
+		if (dev->flags & ATA_DFLAG_DUBIOUS_XFER)
+			eflags |= ATA_EFLAG_DUBIOUS_XFER;
+		ehc->i.action |= ata_eh_speed_down(dev, eflags, all_err_mask);
+	}
+	trace_ata_eh_link_autopsy(dev, ehc->i.action, all_err_mask);
+	DPRINTK("EXIT\n");
+}
+
+/**
+ *	ata_eh_autopsy - analyze error and determine recovery action
+ *	@ap: host port to perform autopsy on
+ *
+ *	Analyze all links of @ap and determine why they failed and
+ *	which recovery actions are needed.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+void ata_eh_autopsy(struct ata_port *ap)
+{
+	struct ata_link *link;
+
+	ata_for_each_link(link, ap, EDGE)
+		ata_eh_link_autopsy(link);
+
+	/* Handle the frigging slave link.  Autopsy is done similarly
+	 * but actions and flags are transferred over to the master
+	 * link and handled from there.
+	 */
+	if (ap->slave_link) {
+		struct ata_eh_context *mehc = &ap->link.eh_context;
+		struct ata_eh_context *sehc = &ap->slave_link->eh_context;
+
+		/* transfer control flags from master to slave */
+		sehc->i.flags |= mehc->i.flags & ATA_EHI_TO_SLAVE_MASK;
+
+		/* perform autopsy on the slave link */
+		ata_eh_link_autopsy(ap->slave_link);
+
+		/* transfer actions from slave to master and clear slave */
+		ata_eh_about_to_do(ap->slave_link, NULL, ATA_EH_ALL_ACTIONS);
+		mehc->i.action		|= sehc->i.action;
+		mehc->i.dev_action[1]	|= sehc->i.dev_action[1];
+		mehc->i.flags		|= sehc->i.flags;
+		ata_eh_done(ap->slave_link, NULL, ATA_EH_ALL_ACTIONS);
+	}
+
+	/* Autopsy of fanout ports can affect host link autopsy.
+	 * Perform host link autopsy last.
+	 */
+	if (sata_pmp_attached(ap))
+		ata_eh_link_autopsy(&ap->link);
+}
+
+/**
+ *	ata_get_cmd_descript - get description for ATA command
+ *	@command: ATA command code to get description for
+ *
+ *	Return a textual description of the given command, or NULL if the
+ *	command is not known.
+ *
+ *	LOCKING:
+ *	None
+ */
+const char *ata_get_cmd_descript(u8 command)
+{
+#ifdef CONFIG_ATA_VERBOSE_ERROR
+	static const struct
+	{
+		u8 command;
+		const char *text;
+	} cmd_descr[] = {
+		{ ATA_CMD_DEV_RESET,		"DEVICE RESET" },
+		{ ATA_CMD_CHK_POWER,		"CHECK POWER MODE" },
+		{ ATA_CMD_STANDBY,		"STANDBY" },
+		{ ATA_CMD_IDLE,			"IDLE" },
+		{ ATA_CMD_EDD,			"EXECUTE DEVICE DIAGNOSTIC" },
+		{ ATA_CMD_DOWNLOAD_MICRO,	"DOWNLOAD MICROCODE" },
+		{ ATA_CMD_DOWNLOAD_MICRO_DMA,	"DOWNLOAD MICROCODE DMA" },
+		{ ATA_CMD_NOP,			"NOP" },
+		{ ATA_CMD_FLUSH,		"FLUSH CACHE" },
+		{ ATA_CMD_FLUSH_EXT,		"FLUSH CACHE EXT" },
+		{ ATA_CMD_ID_ATA,		"IDENTIFY DEVICE" },
+		{ ATA_CMD_ID_ATAPI,		"IDENTIFY PACKET DEVICE" },
+		{ ATA_CMD_SERVICE,		"SERVICE" },
+		{ ATA_CMD_READ,			"READ DMA" },
+		{ ATA_CMD_READ_EXT,		"READ DMA EXT" },
+		{ ATA_CMD_READ_QUEUED,		"READ DMA QUEUED" },
+		{ ATA_CMD_READ_STREAM_EXT,	"READ STREAM EXT" },
+		{ ATA_CMD_READ_STREAM_DMA_EXT,  "READ STREAM DMA EXT" },
+		{ ATA_CMD_WRITE,		"WRITE DMA" },
+		{ ATA_CMD_WRITE_EXT,		"WRITE DMA EXT" },
+		{ ATA_CMD_WRITE_QUEUED,		"WRITE DMA QUEUED EXT" },
+		{ ATA_CMD_WRITE_STREAM_EXT,	"WRITE STREAM EXT" },
+		{ ATA_CMD_WRITE_STREAM_DMA_EXT, "WRITE STREAM DMA EXT" },
+		{ ATA_CMD_WRITE_FUA_EXT,	"WRITE DMA FUA EXT" },
+		{ ATA_CMD_WRITE_QUEUED_FUA_EXT, "WRITE DMA QUEUED FUA EXT" },
+		{ ATA_CMD_FPDMA_READ,		"READ FPDMA QUEUED" },
+		{ ATA_CMD_FPDMA_WRITE,		"WRITE FPDMA QUEUED" },
+		{ ATA_CMD_FPDMA_SEND,		"SEND FPDMA QUEUED" },
+		{ ATA_CMD_FPDMA_RECV,		"RECEIVE FPDMA QUEUED" },
+		{ ATA_CMD_PIO_READ,		"READ SECTOR(S)" },
+		{ ATA_CMD_PIO_READ_EXT,		"READ SECTOR(S) EXT" },
+		{ ATA_CMD_PIO_WRITE,		"WRITE SECTOR(S)" },
+		{ ATA_CMD_PIO_WRITE_EXT,	"WRITE SECTOR(S) EXT" },
+		{ ATA_CMD_READ_MULTI,		"READ MULTIPLE" },
+		{ ATA_CMD_READ_MULTI_EXT,	"READ MULTIPLE EXT" },
+		{ ATA_CMD_WRITE_MULTI,		"WRITE MULTIPLE" },
+		{ ATA_CMD_WRITE_MULTI_EXT,	"WRITE MULTIPLE EXT" },
+		{ ATA_CMD_WRITE_MULTI_FUA_EXT,	"WRITE MULTIPLE FUA EXT" },
+		{ ATA_CMD_SET_FEATURES,		"SET FEATURES" },
+		{ ATA_CMD_SET_MULTI,		"SET MULTIPLE MODE" },
+		{ ATA_CMD_VERIFY,		"READ VERIFY SECTOR(S)" },
+		{ ATA_CMD_VERIFY_EXT,		"READ VERIFY SECTOR(S) EXT" },
+		{ ATA_CMD_WRITE_UNCORR_EXT,	"WRITE UNCORRECTABLE EXT" },
+		{ ATA_CMD_STANDBYNOW1,		"STANDBY IMMEDIATE" },
+		{ ATA_CMD_IDLEIMMEDIATE,	"IDLE IMMEDIATE" },
+		{ ATA_CMD_SLEEP,		"SLEEP" },
+		{ ATA_CMD_INIT_DEV_PARAMS,	"INITIALIZE DEVICE PARAMETERS" },
+		{ ATA_CMD_READ_NATIVE_MAX,	"READ NATIVE MAX ADDRESS" },
+		{ ATA_CMD_READ_NATIVE_MAX_EXT,	"READ NATIVE MAX ADDRESS EXT" },
+		{ ATA_CMD_SET_MAX,		"SET MAX ADDRESS" },
+		{ ATA_CMD_SET_MAX_EXT,		"SET MAX ADDRESS EXT" },
+		{ ATA_CMD_READ_LOG_EXT,		"READ LOG EXT" },
+		{ ATA_CMD_WRITE_LOG_EXT,	"WRITE LOG EXT" },
+		{ ATA_CMD_READ_LOG_DMA_EXT,	"READ LOG DMA EXT" },
+		{ ATA_CMD_WRITE_LOG_DMA_EXT,	"WRITE LOG DMA EXT" },
+		{ ATA_CMD_TRUSTED_NONDATA,	"TRUSTED NON-DATA" },
+		{ ATA_CMD_TRUSTED_RCV,		"TRUSTED RECEIVE" },
+		{ ATA_CMD_TRUSTED_RCV_DMA,	"TRUSTED RECEIVE DMA" },
+		{ ATA_CMD_TRUSTED_SND,		"TRUSTED SEND" },
+		{ ATA_CMD_TRUSTED_SND_DMA,	"TRUSTED SEND DMA" },
+		{ ATA_CMD_PMP_READ,		"READ BUFFER" },
+		{ ATA_CMD_PMP_READ_DMA,		"READ BUFFER DMA" },
+		{ ATA_CMD_PMP_WRITE,		"WRITE BUFFER" },
+		{ ATA_CMD_PMP_WRITE_DMA,	"WRITE BUFFER DMA" },
+		{ ATA_CMD_CONF_OVERLAY,		"DEVICE CONFIGURATION OVERLAY" },
+		{ ATA_CMD_SEC_SET_PASS,		"SECURITY SET PASSWORD" },
+		{ ATA_CMD_SEC_UNLOCK,		"SECURITY UNLOCK" },
+		{ ATA_CMD_SEC_ERASE_PREP,	"SECURITY ERASE PREPARE" },
+		{ ATA_CMD_SEC_ERASE_UNIT,	"SECURITY ERASE UNIT" },
+		{ ATA_CMD_SEC_FREEZE_LOCK,	"SECURITY FREEZE LOCK" },
+		{ ATA_CMD_SEC_DISABLE_PASS,	"SECURITY DISABLE PASSWORD" },
+		{ ATA_CMD_CONFIG_STREAM,	"CONFIGURE STREAM" },
+		{ ATA_CMD_SMART,		"SMART" },
+		{ ATA_CMD_MEDIA_LOCK,		"DOOR LOCK" },
+		{ ATA_CMD_MEDIA_UNLOCK,		"DOOR UNLOCK" },
+		{ ATA_CMD_DSM,			"DATA SET MANAGEMENT" },
+		{ ATA_CMD_CHK_MED_CRD_TYP,	"CHECK MEDIA CARD TYPE" },
+		{ ATA_CMD_CFA_REQ_EXT_ERR,	"CFA REQUEST EXTENDED ERROR" },
+		{ ATA_CMD_CFA_WRITE_NE,		"CFA WRITE SECTORS WITHOUT ERASE" },
+		{ ATA_CMD_CFA_TRANS_SECT,	"CFA TRANSLATE SECTOR" },
+		{ ATA_CMD_CFA_ERASE,		"CFA ERASE SECTORS" },
+		{ ATA_CMD_CFA_WRITE_MULT_NE,	"CFA WRITE MULTIPLE WITHOUT ERASE" },
+		{ ATA_CMD_REQ_SENSE_DATA,	"REQUEST SENSE DATA EXT" },
+		{ ATA_CMD_SANITIZE_DEVICE,	"SANITIZE DEVICE" },
+		{ ATA_CMD_READ_LONG,		"READ LONG (with retries)" },
+		{ ATA_CMD_READ_LONG_ONCE,	"READ LONG (without retries)" },
+		{ ATA_CMD_WRITE_LONG,		"WRITE LONG (with retries)" },
+		{ ATA_CMD_WRITE_LONG_ONCE,	"WRITE LONG (without retries)" },
+		{ ATA_CMD_RESTORE,		"RECALIBRATE" },
+		{ 0,				NULL } /* terminate list */
+	};
+
+	unsigned int i;
+	for (i = 0; cmd_descr[i].text; i++)
+		if (cmd_descr[i].command == command)
+			return cmd_descr[i].text;
+#endif
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(ata_get_cmd_descript);
+
+/**
+ *	ata_eh_link_report - report error handling to user
+ *	@link: ATA link EH is going on
+ *
+ *	Report EH to user.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void ata_eh_link_report(struct ata_link *link)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_eh_context *ehc = &link->eh_context;
+	const char *frozen, *desc;
+	char tries_buf[6] = "";
+	int tag, nr_failed = 0;
+
+	if (ehc->i.flags & ATA_EHI_QUIET)
+		return;
+
+	desc = NULL;
+	if (ehc->i.desc[0] != '\0')
+		desc = ehc->i.desc;
+
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED) ||
+		    ata_dev_phys_link(qc->dev) != link ||
+		    ((qc->flags & ATA_QCFLAG_QUIET) &&
+		     qc->err_mask == AC_ERR_DEV))
+			continue;
+		if (qc->flags & ATA_QCFLAG_SENSE_VALID && !qc->err_mask)
+			continue;
+
+		nr_failed++;
+	}
+
+	if (!nr_failed && !ehc->i.err_mask)
+		return;
+
+	frozen = "";
+	if (ap->pflags & ATA_PFLAG_FROZEN)
+		frozen = " frozen";
+
+	if (ap->eh_tries < ATA_EH_MAX_TRIES)
+		snprintf(tries_buf, sizeof(tries_buf), " t%d",
+			 ap->eh_tries);
+
+	if (ehc->i.dev) {
+		ata_dev_err(ehc->i.dev, "exception Emask 0x%x "
+			    "SAct 0x%x SErr 0x%x action 0x%x%s%s\n",
+			    ehc->i.err_mask, link->sactive, ehc->i.serror,
+			    ehc->i.action, frozen, tries_buf);
+		if (desc)
+			ata_dev_err(ehc->i.dev, "%s\n", desc);
+	} else {
+		ata_link_err(link, "exception Emask 0x%x "
+			     "SAct 0x%x SErr 0x%x action 0x%x%s%s\n",
+			     ehc->i.err_mask, link->sactive, ehc->i.serror,
+			     ehc->i.action, frozen, tries_buf);
+		if (desc)
+			ata_link_err(link, "%s\n", desc);
+	}
+
+#ifdef CONFIG_ATA_VERBOSE_ERROR
+	if (ehc->i.serror)
+		ata_link_err(link,
+		  "SError: { %s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s}\n",
+		  ehc->i.serror & SERR_DATA_RECOVERED ? "RecovData " : "",
+		  ehc->i.serror & SERR_COMM_RECOVERED ? "RecovComm " : "",
+		  ehc->i.serror & SERR_DATA ? "UnrecovData " : "",
+		  ehc->i.serror & SERR_PERSISTENT ? "Persist " : "",
+		  ehc->i.serror & SERR_PROTOCOL ? "Proto " : "",
+		  ehc->i.serror & SERR_INTERNAL ? "HostInt " : "",
+		  ehc->i.serror & SERR_PHYRDY_CHG ? "PHYRdyChg " : "",
+		  ehc->i.serror & SERR_PHY_INT_ERR ? "PHYInt " : "",
+		  ehc->i.serror & SERR_COMM_WAKE ? "CommWake " : "",
+		  ehc->i.serror & SERR_10B_8B_ERR ? "10B8B " : "",
+		  ehc->i.serror & SERR_DISPARITY ? "Dispar " : "",
+		  ehc->i.serror & SERR_CRC ? "BadCRC " : "",
+		  ehc->i.serror & SERR_HANDSHAKE ? "Handshk " : "",
+		  ehc->i.serror & SERR_LINK_SEQ_ERR ? "LinkSeq " : "",
+		  ehc->i.serror & SERR_TRANS_ST_ERROR ? "TrStaTrns " : "",
+		  ehc->i.serror & SERR_UNRECOG_FIS ? "UnrecFIS " : "",
+		  ehc->i.serror & SERR_DEV_XCHG ? "DevExch " : "");
+#endif
+
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
+		struct ata_taskfile *cmd = &qc->tf, *res = &qc->result_tf;
+		char data_buf[20] = "";
+		char cdb_buf[70] = "";
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED) ||
+		    ata_dev_phys_link(qc->dev) != link || !qc->err_mask)
+			continue;
+
+		if (qc->dma_dir != DMA_NONE) {
+			static const char *dma_str[] = {
+				[DMA_BIDIRECTIONAL]	= "bidi",
+				[DMA_TO_DEVICE]		= "out",
+				[DMA_FROM_DEVICE]	= "in",
+			};
+			static const char *prot_str[] = {
+				[ATA_PROT_PIO]		= "pio",
+				[ATA_PROT_DMA]		= "dma",
+				[ATA_PROT_NCQ]		= "ncq",
+				[ATAPI_PROT_PIO]	= "pio",
+				[ATAPI_PROT_DMA]	= "dma",
+			};
+
+			snprintf(data_buf, sizeof(data_buf), " %s %u %s",
+				 prot_str[qc->tf.protocol], qc->nbytes,
+				 dma_str[qc->dma_dir]);
+		}
+
+		if (ata_is_atapi(qc->tf.protocol)) {
+			const u8 *cdb = qc->cdb;
+			size_t cdb_len = qc->dev->cdb_len;
+
+			if (qc->scsicmd) {
+				cdb = qc->scsicmd->cmnd;
+				cdb_len = qc->scsicmd->cmd_len;
+			}
+			__scsi_format_command(cdb_buf, sizeof(cdb_buf),
+					      cdb, cdb_len);
+		} else {
+			const char *descr = ata_get_cmd_descript(cmd->command);
+			if (descr)
+				ata_dev_err(qc->dev, "failed command: %s\n",
+					    descr);
+		}
+
+		ata_dev_err(qc->dev,
+			"cmd %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
+			"tag %d%s\n         %s"
+			"res %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
+			"Emask 0x%x (%s)%s\n",
+			cmd->command, cmd->feature, cmd->nsect,
+			cmd->lbal, cmd->lbam, cmd->lbah,
+			cmd->hob_feature, cmd->hob_nsect,
+			cmd->hob_lbal, cmd->hob_lbam, cmd->hob_lbah,
+			cmd->device, qc->tag, data_buf, cdb_buf,
+			res->command, res->feature, res->nsect,
+			res->lbal, res->lbam, res->lbah,
+			res->hob_feature, res->hob_nsect,
+			res->hob_lbal, res->hob_lbam, res->hob_lbah,
+			res->device, qc->err_mask, ata_err_string(qc->err_mask),
+			qc->err_mask & AC_ERR_NCQ ? " <F>" : "");
+
+#ifdef CONFIG_ATA_VERBOSE_ERROR
+		if (res->command & (ATA_BUSY | ATA_DRDY | ATA_DF | ATA_DRQ |
+				    ATA_SENSE | ATA_ERR)) {
+			if (res->command & ATA_BUSY)
+				ata_dev_err(qc->dev, "status: { Busy }\n");
+			else
+				ata_dev_err(qc->dev, "status: { %s%s%s%s%s}\n",
+				  res->command & ATA_DRDY ? "DRDY " : "",
+				  res->command & ATA_DF ? "DF " : "",
+				  res->command & ATA_DRQ ? "DRQ " : "",
+				  res->command & ATA_SENSE ? "SENSE " : "",
+				  res->command & ATA_ERR ? "ERR " : "");
+		}
+
+		if (cmd->command != ATA_CMD_PACKET &&
+		    (res->feature & (ATA_ICRC | ATA_UNC | ATA_AMNF |
+				     ATA_IDNF | ATA_ABORTED)))
+			ata_dev_err(qc->dev, "error: { %s%s%s%s%s}\n",
+			  res->feature & ATA_ICRC ? "ICRC " : "",
+			  res->feature & ATA_UNC ? "UNC " : "",
+			  res->feature & ATA_AMNF ? "AMNF " : "",
+			  res->feature & ATA_IDNF ? "IDNF " : "",
+			  res->feature & ATA_ABORTED ? "ABRT " : "");
+#endif
+	}
+}
+
+/**
+ *	ata_eh_report - report error handling to user
+ *	@ap: ATA port to report EH about
+ *
+ *	Report EH to user.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_eh_report(struct ata_port *ap)
+{
+	struct ata_link *link;
+
+	ata_for_each_link(link, ap, HOST_FIRST)
+		ata_eh_link_report(link);
+}
+
+static int ata_do_reset(struct ata_link *link, ata_reset_fn_t reset,
+			unsigned int *classes, unsigned long deadline,
+			bool clear_classes)
+{
+	struct ata_device *dev;
+
+	if (clear_classes)
+		ata_for_each_dev(dev, link, ALL)
+			classes[dev->devno] = ATA_DEV_UNKNOWN;
+
+	return reset(link, classes, deadline);
+}
+
+static int ata_eh_followup_srst_needed(struct ata_link *link, int rc)
+{
+	if ((link->flags & ATA_LFLAG_NO_SRST) || ata_link_offline(link))
+		return 0;
+	if (rc == -EAGAIN)
+		return 1;
+	if (sata_pmp_supported(link->ap) && ata_is_host_link(link))
+		return 1;
+	return 0;
+}
+
+int ata_eh_reset(struct ata_link *link, int classify,
+		 ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
+		 ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_link *slave = ap->slave_link;
+	struct ata_eh_context *ehc = &link->eh_context;
+	struct ata_eh_context *sehc = slave ? &slave->eh_context : NULL;
+	unsigned int *classes = ehc->classes;
+	unsigned int lflags = link->flags;
+	int verbose = !(ehc->i.flags & ATA_EHI_QUIET);
+	int max_tries = 0, try = 0;
+	struct ata_link *failed_link;
+	struct ata_device *dev;
+	unsigned long deadline, now;
+	ata_reset_fn_t reset;
+	unsigned long flags;
+	u32 sstatus;
+	int nr_unknown, rc;
+
+	/*
+	 * Prepare to reset
+	 */
+	while (ata_eh_reset_timeouts[max_tries] != ULONG_MAX)
+		max_tries++;
+	if (link->flags & ATA_LFLAG_RST_ONCE)
+		max_tries = 1;
+	if (link->flags & ATA_LFLAG_NO_HRST)
+		hardreset = NULL;
+	if (link->flags & ATA_LFLAG_NO_SRST)
+		softreset = NULL;
+
+	/* make sure each reset attempt is at least COOL_DOWN apart */
+	if (ehc->i.flags & ATA_EHI_DID_RESET) {
+		now = jiffies;
+		WARN_ON(time_after(ehc->last_reset, now));
+		deadline = ata_deadline(ehc->last_reset,
+					ATA_EH_RESET_COOL_DOWN);
+		if (time_before(now, deadline))
+			schedule_timeout_uninterruptible(deadline - now);
+	}
+
+	spin_lock_irqsave(ap->lock, flags);
+	ap->pflags |= ATA_PFLAG_RESETTING;
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	ata_eh_about_to_do(link, NULL, ATA_EH_RESET);
+
+	ata_for_each_dev(dev, link, ALL) {
+		/* If we issue an SRST then an ATA drive (not ATAPI)
+		 * may change configuration and be in PIO0 timing. If
+		 * we do a hard reset (or are coming from power on)
+		 * this is true for ATA or ATAPI. Until we've set a
+		 * suitable controller mode we should not touch the
+		 * bus as we may be talking too fast.
+		 */
+		dev->pio_mode = XFER_PIO_0;
+		dev->dma_mode = 0xff;
+
+		/* If the controller has a pio mode setup function
+		 * then use it to set the chipset to rights. Don't
+		 * touch the DMA setup as that will be dealt with when
+		 * configuring devices.
+		 */
+		if (ap->ops->set_piomode)
+			ap->ops->set_piomode(ap, dev);
+	}
+
+	/* prefer hardreset */
+	reset = NULL;
+	ehc->i.action &= ~ATA_EH_RESET;
+	if (hardreset) {
+		reset = hardreset;
+		ehc->i.action |= ATA_EH_HARDRESET;
+	} else if (softreset) {
+		reset = softreset;
+		ehc->i.action |= ATA_EH_SOFTRESET;
+	}
+
+	if (prereset) {
+		unsigned long deadline = ata_deadline(jiffies,
+						      ATA_EH_PRERESET_TIMEOUT);
+
+		if (slave) {
+			sehc->i.action &= ~ATA_EH_RESET;
+			sehc->i.action |= ehc->i.action;
+		}
+
+		rc = prereset(link, deadline);
+
+		/* If present, do prereset on slave link too.  Reset
+		 * is skipped iff both master and slave links report
+		 * -ENOENT or clear ATA_EH_RESET.
+		 */
+		if (slave && (rc == 0 || rc == -ENOENT)) {
+			int tmp;
+
+			tmp = prereset(slave, deadline);
+			if (tmp != -ENOENT)
+				rc = tmp;
+
+			ehc->i.action |= sehc->i.action;
+		}
+
+		if (rc) {
+			if (rc == -ENOENT) {
+				ata_link_dbg(link, "port disabled--ignoring\n");
+				ehc->i.action &= ~ATA_EH_RESET;
+
+				ata_for_each_dev(dev, link, ALL)
+					classes[dev->devno] = ATA_DEV_NONE;
+
+				rc = 0;
+			} else
+				ata_link_err(link,
+					     "prereset failed (errno=%d)\n",
+					     rc);
+			goto out;
+		}
+
+		/* prereset() might have cleared ATA_EH_RESET.  If so,
+		 * bang classes, thaw and return.
+		 */
+		if (reset && !(ehc->i.action & ATA_EH_RESET)) {
+			ata_for_each_dev(dev, link, ALL)
+				classes[dev->devno] = ATA_DEV_NONE;
+			if ((ap->pflags & ATA_PFLAG_FROZEN) &&
+			    ata_is_host_link(link))
+				ata_eh_thaw_port(ap);
+			rc = 0;
+			goto out;
+		}
+	}
+
+ retry:
+	/*
+	 * Perform reset
+	 */
+	if (ata_is_host_link(link))
+		ata_eh_freeze_port(ap);
+
+	deadline = ata_deadline(jiffies, ata_eh_reset_timeouts[try++]);
+
+	if (reset) {
+		if (verbose)
+			ata_link_info(link, "%s resetting link\n",
+				      reset == softreset ? "soft" : "hard");
+
+		/* mark that this EH session started with reset */
+		ehc->last_reset = jiffies;
+		if (reset == hardreset)
+			ehc->i.flags |= ATA_EHI_DID_HARDRESET;
+		else
+			ehc->i.flags |= ATA_EHI_DID_SOFTRESET;
+
+		rc = ata_do_reset(link, reset, classes, deadline, true);
+		if (rc && rc != -EAGAIN) {
+			failed_link = link;
+			goto fail;
+		}
+
+		/* hardreset slave link if existent */
+		if (slave && reset == hardreset) {
+			int tmp;
+
+			if (verbose)
+				ata_link_info(slave, "hard resetting link\n");
+
+			ata_eh_about_to_do(slave, NULL, ATA_EH_RESET);
+			tmp = ata_do_reset(slave, reset, classes, deadline,
+					   false);
+			switch (tmp) {
+			case -EAGAIN:
+				rc = -EAGAIN;
+			case 0:
+				break;
+			default:
+				failed_link = slave;
+				rc = tmp;
+				goto fail;
+			}
+		}
+
+		/* perform follow-up SRST if necessary */
+		if (reset == hardreset &&
+		    ata_eh_followup_srst_needed(link, rc)) {
+			reset = softreset;
+
+			if (!reset) {
+				ata_link_err(link,
+	     "follow-up softreset required but no softreset available\n");
+				failed_link = link;
+				rc = -EINVAL;
+				goto fail;
+			}
+
+			ata_eh_about_to_do(link, NULL, ATA_EH_RESET);
+			rc = ata_do_reset(link, reset, classes, deadline, true);
+			if (rc) {
+				failed_link = link;
+				goto fail;
+			}
+		}
+	} else {
+		if (verbose)
+			ata_link_info(link,
+	"no reset method available, skipping reset\n");
+		if (!(lflags & ATA_LFLAG_ASSUME_CLASS))
+			lflags |= ATA_LFLAG_ASSUME_ATA;
+	}
+
+	/*
+	 * Post-reset processing
+	 */
+	ata_for_each_dev(dev, link, ALL) {
+		/* After the reset, the device state is PIO 0 and the
+		 * controller state is undefined.  Reset also wakes up
+		 * drives from sleeping mode.
+		 */
+		dev->pio_mode = XFER_PIO_0;
+		dev->flags &= ~ATA_DFLAG_SLEEPING;
+
+		if (ata_phys_link_offline(ata_dev_phys_link(dev)))
+			continue;
+
+		/* apply class override */
+		if (lflags & ATA_LFLAG_ASSUME_ATA)
+			classes[dev->devno] = ATA_DEV_ATA;
+		else if (lflags & ATA_LFLAG_ASSUME_SEMB)
+			classes[dev->devno] = ATA_DEV_SEMB_UNSUP;
+	}
+
+	/* record current link speed */
+	if (sata_scr_read(link, SCR_STATUS, &sstatus) == 0)
+		link->sata_spd = (sstatus >> 4) & 0xf;
+	if (slave && sata_scr_read(slave, SCR_STATUS, &sstatus) == 0)
+		slave->sata_spd = (sstatus >> 4) & 0xf;
+
+	/* thaw the port */
+	if (ata_is_host_link(link))
+		ata_eh_thaw_port(ap);
+
+	/* postreset() should clear hardware SError.  Although SError
+	 * is cleared during link resume, clearing SError here is
+	 * necessary as some PHYs raise hotplug events after SRST.
+	 * This introduces race condition where hotplug occurs between
+	 * reset and here.  This race is mediated by cross checking
+	 * link onlineness and classification result later.
+	 */
+	if (postreset) {
+		postreset(link, classes);
+		if (slave)
+			postreset(slave, classes);
+	}
+
+	/*
+	 * Some controllers can't be frozen very well and may set spurious
+	 * error conditions during reset.  Clear accumulated error
+	 * information and re-thaw the port if frozen.  As reset is the
+	 * final recovery action and we cross check link onlineness against
+	 * device classification later, no hotplug event is lost by this.
+	 */
+	spin_lock_irqsave(link->ap->lock, flags);
+	memset(&link->eh_info, 0, sizeof(link->eh_info));
+	if (slave)
+		memset(&slave->eh_info, 0, sizeof(link->eh_info));
+	ap->pflags &= ~ATA_PFLAG_EH_PENDING;
+	spin_unlock_irqrestore(link->ap->lock, flags);
+
+	if (ap->pflags & ATA_PFLAG_FROZEN)
+		ata_eh_thaw_port(ap);
+
+	/*
+	 * Make sure onlineness and classification result correspond.
+	 * Hotplug could have happened during reset and some
+	 * controllers fail to wait while a drive is spinning up after
+	 * being hotplugged causing misdetection.  By cross checking
+	 * link on/offlineness and classification result, those
+	 * conditions can be reliably detected and retried.
+	 */
+	nr_unknown = 0;
+	ata_for_each_dev(dev, link, ALL) {
+		if (ata_phys_link_online(ata_dev_phys_link(dev))) {
+			if (classes[dev->devno] == ATA_DEV_UNKNOWN) {
+				ata_dev_dbg(dev, "link online but device misclassified\n");
+				classes[dev->devno] = ATA_DEV_NONE;
+				nr_unknown++;
+			}
+		} else if (ata_phys_link_offline(ata_dev_phys_link(dev))) {
+			if (ata_class_enabled(classes[dev->devno]))
+				ata_dev_dbg(dev,
+					    "link offline, clearing class %d to NONE\n",
+					    classes[dev->devno]);
+			classes[dev->devno] = ATA_DEV_NONE;
+		} else if (classes[dev->devno] == ATA_DEV_UNKNOWN) {
+			ata_dev_dbg(dev,
+				    "link status unknown, clearing UNKNOWN to NONE\n");
+			classes[dev->devno] = ATA_DEV_NONE;
+		}
+	}
+
+	if (classify && nr_unknown) {
+		if (try < max_tries) {
+			ata_link_warn(link,
+				      "link online but %d devices misclassified, retrying\n",
+				      nr_unknown);
+			failed_link = link;
+			rc = -EAGAIN;
+			goto fail;
+		}
+		ata_link_warn(link,
+			      "link online but %d devices misclassified, "
+			      "device detection might fail\n", nr_unknown);
+	}
+
+	/* reset successful, schedule revalidation */
+	ata_eh_done(link, NULL, ATA_EH_RESET);
+	if (slave)
+		ata_eh_done(slave, NULL, ATA_EH_RESET);
+	ehc->last_reset = jiffies;		/* update to completion time */
+	ehc->i.action |= ATA_EH_REVALIDATE;
+	link->lpm_policy = ATA_LPM_UNKNOWN;	/* reset LPM state */
+
+	rc = 0;
+ out:
+	/* clear hotplug flag */
+	ehc->i.flags &= ~ATA_EHI_HOTPLUGGED;
+	if (slave)
+		sehc->i.flags &= ~ATA_EHI_HOTPLUGGED;
+
+	spin_lock_irqsave(ap->lock, flags);
+	ap->pflags &= ~ATA_PFLAG_RESETTING;
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	return rc;
+
+ fail:
+	/* if SCR isn't accessible on a fan-out port, PMP needs to be reset */
+	if (!ata_is_host_link(link) &&
+	    sata_scr_read(link, SCR_STATUS, &sstatus))
+		rc = -ERESTART;
+
+	if (try >= max_tries) {
+		/*
+		 * Thaw host port even if reset failed, so that the port
+		 * can be retried on the next phy event.  This risks
+		 * repeated EH runs but seems to be a better tradeoff than
+		 * shutting down a port after a botched hotplug attempt.
+		 */
+		if (ata_is_host_link(link))
+			ata_eh_thaw_port(ap);
+		goto out;
+	}
+
+	now = jiffies;
+	if (time_before(now, deadline)) {
+		unsigned long delta = deadline - now;
+
+		ata_link_warn(failed_link,
+			"reset failed (errno=%d), retrying in %u secs\n",
+			rc, DIV_ROUND_UP(jiffies_to_msecs(delta), 1000));
+
+		ata_eh_release(ap);
+		while (delta)
+			delta = schedule_timeout_uninterruptible(delta);
+		ata_eh_acquire(ap);
+	}
+
+	/*
+	 * While disks spinup behind PMP, some controllers fail sending SRST.
+	 * They need to be reset - as well as the PMP - before retrying.
+	 */
+	if (rc == -ERESTART) {
+		if (ata_is_host_link(link))
+			ata_eh_thaw_port(ap);
+		goto out;
+	}
+
+	if (try == max_tries - 1) {
+		sata_down_spd_limit(link, 0);
+		if (slave)
+			sata_down_spd_limit(slave, 0);
+	} else if (rc == -EPIPE)
+		sata_down_spd_limit(failed_link, 0);
+
+	if (hardreset)
+		reset = hardreset;
+	goto retry;
+}
+
+static inline void ata_eh_pull_park_action(struct ata_port *ap)
+{
+	struct ata_link *link;
+	struct ata_device *dev;
+	unsigned long flags;
+
+	/*
+	 * This function can be thought of as an extended version of
+	 * ata_eh_about_to_do() specially crafted to accommodate the
+	 * requirements of ATA_EH_PARK handling. Since the EH thread
+	 * does not leave the do {} while () loop in ata_eh_recover as
+	 * long as the timeout for a park request to *one* device on
+	 * the port has not expired, and since we still want to pick
+	 * up park requests to other devices on the same port or
+	 * timeout updates for the same device, we have to pull
+	 * ATA_EH_PARK actions from eh_info into eh_context.i
+	 * ourselves at the beginning of each pass over the loop.
+	 *
+	 * Additionally, all write accesses to &ap->park_req_pending
+	 * through reinit_completion() (see below) or complete_all()
+	 * (see ata_scsi_park_store()) are protected by the host lock.
+	 * As a result we have that park_req_pending.done is zero on
+	 * exit from this function, i.e. when ATA_EH_PARK actions for
+	 * *all* devices on port ap have been pulled into the
+	 * respective eh_context structs. If, and only if,
+	 * park_req_pending.done is non-zero by the time we reach
+	 * wait_for_completion_timeout(), another ATA_EH_PARK action
+	 * has been scheduled for at least one of the devices on port
+	 * ap and we have to cycle over the do {} while () loop in
+	 * ata_eh_recover() again.
+	 */
+
+	spin_lock_irqsave(ap->lock, flags);
+	reinit_completion(&ap->park_req_pending);
+	ata_for_each_link(link, ap, EDGE) {
+		ata_for_each_dev(dev, link, ALL) {
+			struct ata_eh_info *ehi = &link->eh_info;
+
+			link->eh_context.i.dev_action[dev->devno] |=
+				ehi->dev_action[dev->devno] & ATA_EH_PARK;
+			ata_eh_clear_action(link, dev, ehi, ATA_EH_PARK);
+		}
+	}
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+static void ata_eh_park_issue_cmd(struct ata_device *dev, int park)
+{
+	struct ata_eh_context *ehc = &dev->link->eh_context;
+	struct ata_taskfile tf;
+	unsigned int err_mask;
+
+	ata_tf_init(dev, &tf);
+	if (park) {
+		ehc->unloaded_mask |= 1 << dev->devno;
+		tf.command = ATA_CMD_IDLEIMMEDIATE;
+		tf.feature = 0x44;
+		tf.lbal = 0x4c;
+		tf.lbam = 0x4e;
+		tf.lbah = 0x55;
+	} else {
+		ehc->unloaded_mask &= ~(1 << dev->devno);
+		tf.command = ATA_CMD_CHK_POWER;
+	}
+
+	tf.flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;
+	tf.protocol |= ATA_PROT_NODATA;
+	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
+	if (park && (err_mask || tf.lbal != 0xc4)) {
+		ata_dev_err(dev, "head unload failed!\n");
+		ehc->unloaded_mask &= ~(1 << dev->devno);
+	}
+}
+
+static int ata_eh_revalidate_and_attach(struct ata_link *link,
+					struct ata_device **r_failed_dev)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_eh_context *ehc = &link->eh_context;
+	struct ata_device *dev;
+	unsigned int new_mask = 0;
+	unsigned long flags;
+	int rc = 0;
+
+	DPRINTK("ENTER\n");
+
+	/* For PATA drive side cable detection to work, IDENTIFY must
+	 * be done backwards such that PDIAG- is released by the slave
+	 * device before the master device is identified.
+	 */
+	ata_for_each_dev(dev, link, ALL_REVERSE) {
+		unsigned int action = ata_eh_dev_action(dev);
+		unsigned int readid_flags = 0;
+
+		if (ehc->i.flags & ATA_EHI_DID_RESET)
+			readid_flags |= ATA_READID_POSTRESET;
+
+		if ((action & ATA_EH_REVALIDATE) && ata_dev_enabled(dev)) {
+			WARN_ON(dev->class == ATA_DEV_PMP);
+
+			if (ata_phys_link_offline(ata_dev_phys_link(dev))) {
+				rc = -EIO;
+				goto err;
+			}
+
+			ata_eh_about_to_do(link, dev, ATA_EH_REVALIDATE);
+			rc = ata_dev_revalidate(dev, ehc->classes[dev->devno],
+						readid_flags);
+			if (rc)
+				goto err;
+
+			ata_eh_done(link, dev, ATA_EH_REVALIDATE);
+
+			/* Configuration may have changed, reconfigure
+			 * transfer mode.
+			 */
+			ehc->i.flags |= ATA_EHI_SETMODE;
+
+			/* schedule the scsi_rescan_device() here */
+			schedule_work(&(ap->scsi_rescan_task));
+		} else if (dev->class == ATA_DEV_UNKNOWN &&
+			   ehc->tries[dev->devno] &&
+			   ata_class_enabled(ehc->classes[dev->devno])) {
+			/* Temporarily set dev->class, it will be
+			 * permanently set once all configurations are
+			 * complete.  This is necessary because new
+			 * device configuration is done in two
+			 * separate loops.
+			 */
+			dev->class = ehc->classes[dev->devno];
+
+			if (dev->class == ATA_DEV_PMP)
+				rc = sata_pmp_attach(dev);
+			else
+				rc = ata_dev_read_id(dev, &dev->class,
+						     readid_flags, dev->id);
+
+			/* read_id might have changed class, store and reset */
+			ehc->classes[dev->devno] = dev->class;
+			dev->class = ATA_DEV_UNKNOWN;
+
+			switch (rc) {
+			case 0:
+				/* clear error info accumulated during probe */
+				ata_ering_clear(&dev->ering);
+				new_mask |= 1 << dev->devno;
+				break;
+			case -ENOENT:
+				/* IDENTIFY was issued to non-existent
+				 * device.  No need to reset.  Just
+				 * thaw and ignore the device.
+				 */
+				ata_eh_thaw_port(ap);
+				break;
+			default:
+				goto err;
+			}
+		}
+	}
+
+	/* PDIAG- should have been released, ask cable type if post-reset */
+	if ((ehc->i.flags & ATA_EHI_DID_RESET) && ata_is_host_link(link)) {
+		if (ap->ops->cable_detect)
+			ap->cbl = ap->ops->cable_detect(ap);
+		ata_force_cbl(ap);
+	}
+
+	/* Configure new devices forward such that user doesn't see
+	 * device detection messages backwards.
+	 */
+	ata_for_each_dev(dev, link, ALL) {
+		if (!(new_mask & (1 << dev->devno)))
+			continue;
+
+		dev->class = ehc->classes[dev->devno];
+
+		if (dev->class == ATA_DEV_PMP)
+			continue;
+
+		ehc->i.flags |= ATA_EHI_PRINTINFO;
+		rc = ata_dev_configure(dev);
+		ehc->i.flags &= ~ATA_EHI_PRINTINFO;
+		if (rc) {
+			dev->class = ATA_DEV_UNKNOWN;
+			goto err;
+		}
+
+		spin_lock_irqsave(ap->lock, flags);
+		ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
+		spin_unlock_irqrestore(ap->lock, flags);
+
+		/* new device discovered, configure xfermode */
+		ehc->i.flags |= ATA_EHI_SETMODE;
+	}
+
+	return 0;
+
+ err:
+	*r_failed_dev = dev;
+	DPRINTK("EXIT rc=%d\n", rc);
+	return rc;
+}
+
+/**
+ *	ata_set_mode - Program timings and issue SET FEATURES - XFER
+ *	@link: link on which timings will be programmed
+ *	@r_failed_dev: out parameter for failed device
+ *
+ *	Set ATA device disk transfer mode (PIO3, UDMA6, etc.).  If
+ *	ata_set_mode() fails, pointer to the failing device is
+ *	returned in @r_failed_dev.
+ *
+ *	LOCKING:
+ *	PCI/etc. bus probe sem.
+ *
+ *	RETURNS:
+ *	0 on success, negative errno otherwise
+ */
+int ata_set_mode(struct ata_link *link, struct ata_device **r_failed_dev)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_device *dev;
+	int rc;
+
+	/* if data transfer is verified, clear DUBIOUS_XFER on ering top */
+	ata_for_each_dev(dev, link, ENABLED) {
+		if (!(dev->flags & ATA_DFLAG_DUBIOUS_XFER)) {
+			struct ata_ering_entry *ent;
+
+			ent = ata_ering_top(&dev->ering);
+			if (ent)
+				ent->eflags &= ~ATA_EFLAG_DUBIOUS_XFER;
+		}
+	}
+
+	/* has private set_mode? */
+	if (ap->ops->set_mode)
+		rc = ap->ops->set_mode(link, r_failed_dev);
+	else
+		rc = ata_do_set_mode(link, r_failed_dev);
+
+	/* if transfer mode has changed, set DUBIOUS_XFER on device */
+	ata_for_each_dev(dev, link, ENABLED) {
+		struct ata_eh_context *ehc = &link->eh_context;
+		u8 saved_xfer_mode = ehc->saved_xfer_mode[dev->devno];
+		u8 saved_ncq = !!(ehc->saved_ncq_enabled & (1 << dev->devno));
+
+		if (dev->xfer_mode != saved_xfer_mode ||
+		    ata_ncq_enabled(dev) != saved_ncq)
+			dev->flags |= ATA_DFLAG_DUBIOUS_XFER;
+	}
+
+	return rc;
+}
+
+/**
+ *	atapi_eh_clear_ua - Clear ATAPI UNIT ATTENTION after reset
+ *	@dev: ATAPI device to clear UA for
+ *
+ *	Resets and other operations can make an ATAPI device raise
+ *	UNIT ATTENTION which causes the next operation to fail.  This
+ *	function clears UA.
+ *
+ *	LOCKING:
+ *	EH context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int atapi_eh_clear_ua(struct ata_device *dev)
+{
+	int i;
+
+	for (i = 0; i < ATA_EH_UA_TRIES; i++) {
+		u8 *sense_buffer = dev->link->ap->sector_buf;
+		u8 sense_key = 0;
+		unsigned int err_mask;
+
+		err_mask = atapi_eh_tur(dev, &sense_key);
+		if (err_mask != 0 && err_mask != AC_ERR_DEV) {
+			ata_dev_warn(dev,
+				     "TEST_UNIT_READY failed (err_mask=0x%x)\n",
+				     err_mask);
+			return -EIO;
+		}
+
+		if (!err_mask || sense_key != UNIT_ATTENTION)
+			return 0;
+
+		err_mask = atapi_eh_request_sense(dev, sense_buffer, sense_key);
+		if (err_mask) {
+			ata_dev_warn(dev, "failed to clear "
+				"UNIT ATTENTION (err_mask=0x%x)\n", err_mask);
+			return -EIO;
+		}
+	}
+
+	ata_dev_warn(dev, "UNIT ATTENTION persists after %d tries\n",
+		     ATA_EH_UA_TRIES);
+
+	return 0;
+}
+
+/**
+ *	ata_eh_maybe_retry_flush - Retry FLUSH if necessary
+ *	@dev: ATA device which may need FLUSH retry
+ *
+ *	If @dev failed FLUSH, it needs to be reported upper layer
+ *	immediately as it means that @dev failed to remap and already
+ *	lost at least a sector and further FLUSH retrials won't make
+ *	any difference to the lost sector.  However, if FLUSH failed
+ *	for other reasons, for example transmission error, FLUSH needs
+ *	to be retried.
+ *
+ *	This function determines whether FLUSH failure retry is
+ *	necessary and performs it if so.
+ *
+ *	RETURNS:
+ *	0 if EH can continue, -errno if EH needs to be repeated.
+ */
+static int ata_eh_maybe_retry_flush(struct ata_device *dev)
+{
+	struct ata_link *link = dev->link;
+	struct ata_port *ap = link->ap;
+	struct ata_queued_cmd *qc;
+	struct ata_taskfile tf;
+	unsigned int err_mask;
+	int rc = 0;
+
+	/* did flush fail for this device? */
+	if (!ata_tag_valid(link->active_tag))
+		return 0;
+
+	qc = __ata_qc_from_tag(ap, link->active_tag);
+	if (qc->dev != dev || (qc->tf.command != ATA_CMD_FLUSH_EXT &&
+			       qc->tf.command != ATA_CMD_FLUSH))
+		return 0;
+
+	/* if the device failed it, it should be reported to upper layers */
+	if (qc->err_mask & AC_ERR_DEV)
+		return 0;
+
+	/* flush failed for some other reason, give it another shot */
+	ata_tf_init(dev, &tf);
+
+	tf.command = qc->tf.command;
+	tf.flags |= ATA_TFLAG_DEVICE;
+	tf.protocol = ATA_PROT_NODATA;
+
+	ata_dev_warn(dev, "retrying FLUSH 0x%x Emask 0x%x\n",
+		       tf.command, qc->err_mask);
+
+	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
+	if (!err_mask) {
+		/*
+		 * FLUSH is complete but there's no way to
+		 * successfully complete a failed command from EH.
+		 * Making sure retry is allowed at least once and
+		 * retrying it should do the trick - whatever was in
+		 * the cache is already on the platter and this won't
+		 * cause infinite loop.
+		 */
+		qc->scsicmd->allowed = max(qc->scsicmd->allowed, 1);
+	} else {
+		ata_dev_warn(dev, "FLUSH failed Emask 0x%x\n",
+			       err_mask);
+		rc = -EIO;
+
+		/* if device failed it, report it to upper layers */
+		if (err_mask & AC_ERR_DEV) {
+			qc->err_mask |= AC_ERR_DEV;
+			qc->result_tf = tf;
+			if (!(ap->pflags & ATA_PFLAG_FROZEN))
+				rc = 0;
+		}
+	}
+	return rc;
+}
+
+/**
+ *	ata_eh_set_lpm - configure SATA interface power management
+ *	@link: link to configure power management
+ *	@policy: the link power management policy
+ *	@r_failed_dev: out parameter for failed device
+ *
+ *	Enable SATA Interface power management.  This will enable
+ *	Device Interface Power Management (DIPM) for min_power
+ * 	policy, and then call driver specific callbacks for
+ *	enabling Host Initiated Power management.
+ *
+ *	LOCKING:
+ *	EH context.
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
+			  struct ata_device **r_failed_dev)
+{
+	struct ata_port *ap = ata_is_host_link(link) ? link->ap : NULL;
+	struct ata_eh_context *ehc = &link->eh_context;
+	struct ata_device *dev, *link_dev = NULL, *lpm_dev = NULL;
+	enum ata_lpm_policy old_policy = link->lpm_policy;
+	bool no_dipm = link->ap->flags & ATA_FLAG_NO_DIPM;
+	unsigned int hints = ATA_LPM_EMPTY | ATA_LPM_HIPM;
+	unsigned int err_mask;
+	int rc;
+
+	/* if the link or host doesn't do LPM, noop */
+	if ((link->flags & ATA_LFLAG_NO_LPM) || (ap && !ap->ops->set_lpm))
+		return 0;
+
+	/*
+	 * DIPM is enabled only for MIN_POWER and FIRMWARE_DEFAULT as some
+	 * devices misbehave when the host NACKs transition to SLUMBER.
+	 * Order device and link configurations such that the host always
+	 * allows DIPM requests.
+	 */
+	ata_for_each_dev(dev, link, ENABLED) {
+		bool hipm = ata_id_has_hipm(dev->id);
+		bool dipm = ata_id_has_dipm(dev->id) && !no_dipm;
+
+		/* find the first enabled and LPM enabled devices */
+		if (!link_dev)
+			link_dev = dev;
+
+		if (!lpm_dev && (hipm || dipm))
+			lpm_dev = dev;
+
+		hints &= ~ATA_LPM_EMPTY;
+		if (!hipm)
+			hints &= ~ATA_LPM_HIPM;
+
+		/* disable DIPM before changing link config */
+		if (policy != ATA_LPM_MIN_POWER && dipm) {
+			err_mask = ata_dev_set_feature(dev,
+					SETFEATURES_SATA_DISABLE, SATA_DIPM);
+			if (err_mask && err_mask != AC_ERR_DEV) {
+				ata_dev_warn(dev,
+					     "failed to disable DIPM, Emask 0x%x\n",
+					     err_mask);
+				rc = -EIO;
+				goto fail;
+			}
+		}
+	}
+
+	if (ap) {
+		rc = ap->ops->set_lpm(link, policy, hints);
+		if (!rc && ap->slave_link)
+			rc = ap->ops->set_lpm(ap->slave_link, policy, hints);
+	} else
+		rc = sata_pmp_set_lpm(link, policy, hints);
+
+	/*
+	 * Attribute link config failure to the first (LPM) enabled
+	 * device on the link.
+	 */
+	if (rc) {
+		if (rc == -EOPNOTSUPP) {
+			link->flags |= ATA_LFLAG_NO_LPM;
+			return 0;
+		}
+		dev = lpm_dev ? lpm_dev : link_dev;
+		goto fail;
+	}
+
+	/*
+	 * Low level driver acked the transition.  Issue DIPM command
+	 * with the new policy set.
+	 */
+	link->lpm_policy = policy;
+	if (ap && ap->slave_link)
+		ap->slave_link->lpm_policy = policy;
+
+	/* host config updated, enable DIPM if transitioning to MIN_POWER or
+	 * FIRMWARE_DEFAULT when enabled by firmware
+	 */
+	ata_for_each_dev(dev, link, ENABLED) {
+		if ((policy == ATA_LPM_MIN_POWER && !no_dipm &&
+		     ata_id_has_dipm(dev->id)) ||
+		    (policy == ATA_LPM_FIRMWARE_DEFAULTS && dev->init_dipm)) {
+			err_mask = ata_dev_set_feature(dev,
+					SETFEATURES_SATA_ENABLE, SATA_DIPM);
+			if (err_mask && err_mask != AC_ERR_DEV) {
+				ata_dev_warn(dev,
+					"failed to enable DIPM, Emask 0x%x\n",
+					err_mask);
+				rc = -EIO;
+				goto fail;
+			}
+		}
+	}
+
+	link->last_lpm_change = jiffies;
+	link->flags |= ATA_LFLAG_CHANGED;
+
+	return 0;
+
+fail:
+	/* restore the old policy */
+	link->lpm_policy = old_policy;
+	if (ap && ap->slave_link)
+		ap->slave_link->lpm_policy = old_policy;
+
+	/* if no device or only one more chance is left, disable LPM */
+	if (!dev || ehc->tries[dev->devno] <= 2) {
+		ata_link_warn(link, "disabling LPM on the link\n");
+		link->flags |= ATA_LFLAG_NO_LPM;
+	}
+	if (r_failed_dev)
+		*r_failed_dev = dev;
+	return rc;
+}
+
+int ata_link_nr_enabled(struct ata_link *link)
+{
+	struct ata_device *dev;
+	int cnt = 0;
+
+	ata_for_each_dev(dev, link, ENABLED)
+		cnt++;
+	return cnt;
+}
+
+static int ata_link_nr_vacant(struct ata_link *link)
+{
+	struct ata_device *dev;
+	int cnt = 0;
+
+	ata_for_each_dev(dev, link, ALL)
+		if (dev->class == ATA_DEV_UNKNOWN)
+			cnt++;
+	return cnt;
+}
+
+static int ata_eh_skip_recovery(struct ata_link *link)
+{
+	struct ata_port *ap = link->ap;
+	struct ata_eh_context *ehc = &link->eh_context;
+	struct ata_device *dev;
+
+	/* skip disabled links */
+	if (link->flags & ATA_LFLAG_DISABLED)
+		return 1;
+
+	/* skip if explicitly requested */
+	if (ehc->i.flags & ATA_EHI_NO_RECOVERY)
+		return 1;
+
+	/* thaw frozen port and recover failed devices */
+	if ((ap->pflags & ATA_PFLAG_FROZEN) || ata_link_nr_enabled(link))
+		return 0;
+
+	/* reset at least once if reset is requested */
+	if ((ehc->i.action & ATA_EH_RESET) &&
+	    !(ehc->i.flags & ATA_EHI_DID_RESET))
+		return 0;
+
+	/* skip if class codes for all vacant slots are ATA_DEV_NONE */
+	ata_for_each_dev(dev, link, ALL) {
+		if (dev->class == ATA_DEV_UNKNOWN &&
+		    ehc->classes[dev->devno] != ATA_DEV_NONE)
+			return 0;
+	}
+
+	return 1;
+}
+
+static int ata_count_probe_trials_cb(struct ata_ering_entry *ent, void *void_arg)
+{
+	u64 interval = msecs_to_jiffies(ATA_EH_PROBE_TRIAL_INTERVAL);
+	u64 now = get_jiffies_64();
+	int *trials = void_arg;
+
+	if ((ent->eflags & ATA_EFLAG_OLD_ER) ||
+	    (ent->timestamp < now - min(now, interval)))
+		return -1;
+
+	(*trials)++;
+	return 0;
+}
+
+static int ata_eh_schedule_probe(struct ata_device *dev)
+{
+	struct ata_eh_context *ehc = &dev->link->eh_context;
+	struct ata_link *link = ata_dev_phys_link(dev);
+	int trials = 0;
+
+	if (!(ehc->i.probe_mask & (1 << dev->devno)) ||
+	    (ehc->did_probe_mask & (1 << dev->devno)))
+		return 0;
+
+	ata_eh_detach_dev(dev);
+	ata_dev_init(dev);
+	ehc->did_probe_mask |= (1 << dev->devno);
+	ehc->i.action |= ATA_EH_RESET;
+	ehc->saved_xfer_mode[dev->devno] = 0;
+	ehc->saved_ncq_enabled &= ~(1 << dev->devno);
+
+	/* the link maybe in a deep sleep, wake it up */
+	if (link->lpm_policy > ATA_LPM_MAX_POWER) {
+		if (ata_is_host_link(link))
+			link->ap->ops->set_lpm(link, ATA_LPM_MAX_POWER,
+					       ATA_LPM_EMPTY);
+		else
+			sata_pmp_set_lpm(link, ATA_LPM_MAX_POWER,
+					 ATA_LPM_EMPTY);
+	}
+
+	/* Record and count probe trials on the ering.  The specific
+	 * error mask used is irrelevant.  Because a successful device
+	 * detection clears the ering, this count accumulates only if
+	 * there are consecutive failed probes.
+	 *
+	 * If the count is equal to or higher than ATA_EH_PROBE_TRIALS
+	 * in the last ATA_EH_PROBE_TRIAL_INTERVAL, link speed is
+	 * forced to 1.5Gbps.
+	 *
+	 * This is to work around cases where failed link speed
+	 * negotiation results in device misdetection leading to
+	 * infinite DEVXCHG or PHRDY CHG events.
+	 */
+	ata_ering_record(&dev->ering, 0, AC_ERR_OTHER);
+	ata_ering_map(&dev->ering, ata_count_probe_trials_cb, &trials);
+
+	if (trials > ATA_EH_PROBE_TRIALS)
+		sata_down_spd_limit(link, 1);
+
+	return 1;
+}
+
+static int ata_eh_handle_dev_fail(struct ata_device *dev, int err)
+{
+	struct ata_eh_context *ehc = &dev->link->eh_context;
+
+	/* -EAGAIN from EH routine indicates retry without prejudice.
+	 * The requester is responsible for ensuring forward progress.
+	 */
+	if (err != -EAGAIN)
+		ehc->tries[dev->devno]--;
+
+	switch (err) {
+	case -ENODEV:
+		/* device missing or wrong IDENTIFY data, schedule probing */
+		ehc->i.probe_mask |= (1 << dev->devno);
+	case -EINVAL:
+		/* give it just one more chance */
+		ehc->tries[dev->devno] = min(ehc->tries[dev->devno], 1);
+	case -EIO:
+		if (ehc->tries[dev->devno] == 1) {
+			/* This is the last chance, better to slow
+			 * down than lose it.
+			 */
+			sata_down_spd_limit(ata_dev_phys_link(dev), 0);
+			if (dev->pio_mode > XFER_PIO_0)
+				ata_down_xfermask_limit(dev, ATA_DNXFER_PIO);
+		}
+	}
+
+	if (ata_dev_enabled(dev) && !ehc->tries[dev->devno]) {
+		/* disable device if it has used up all its chances */
+		ata_dev_disable(dev);
+
+		/* detach if offline */
+		if (ata_phys_link_offline(ata_dev_phys_link(dev)))
+			ata_eh_detach_dev(dev);
+
+		/* schedule probe if necessary */
+		if (ata_eh_schedule_probe(dev)) {
+			ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
+			memset(ehc->cmd_timeout_idx[dev->devno], 0,
+			       sizeof(ehc->cmd_timeout_idx[dev->devno]));
+		}
+
+		return 1;
+	} else {
+		ehc->i.action |= ATA_EH_RESET;
+		return 0;
+	}
+}
+
+/**
+ *	ata_eh_recover - recover host port after error
+ *	@ap: host port to recover
+ *	@prereset: prereset method (can be NULL)
+ *	@softreset: softreset method (can be NULL)
+ *	@hardreset: hardreset method (can be NULL)
+ *	@postreset: postreset method (can be NULL)
+ *	@r_failed_link: out parameter for failed link
+ *
+ *	This is the alpha and omega, eum and yang, heart and soul of
+ *	libata exception handling.  On entry, actions required to
+ *	recover each link and hotplug requests are recorded in the
+ *	link's eh_context.  This function executes all the operations
+ *	with appropriate retrials and fallbacks to resurrect failed
+ *	devices, detach goners and greet newcomers.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
+		   ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
+		   ata_postreset_fn_t postreset,
+		   struct ata_link **r_failed_link)
+{
+	struct ata_link *link;
+	struct ata_device *dev;
+	int rc, nr_fails;
+	unsigned long flags, deadline;
+
+	DPRINTK("ENTER\n");
+
+	/* prep for recovery */
+	ata_for_each_link(link, ap, EDGE) {
+		struct ata_eh_context *ehc = &link->eh_context;
+
+		/* re-enable link? */
+		if (ehc->i.action & ATA_EH_ENABLE_LINK) {
+			ata_eh_about_to_do(link, NULL, ATA_EH_ENABLE_LINK);
+			spin_lock_irqsave(ap->lock, flags);
+			link->flags &= ~ATA_LFLAG_DISABLED;
+			spin_unlock_irqrestore(ap->lock, flags);
+			ata_eh_done(link, NULL, ATA_EH_ENABLE_LINK);
+		}
+
+		ata_for_each_dev(dev, link, ALL) {
+			if (link->flags & ATA_LFLAG_NO_RETRY)
+				ehc->tries[dev->devno] = 1;
+			else
+				ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
+
+			/* collect port action mask recorded in dev actions */
+			ehc->i.action |= ehc->i.dev_action[dev->devno] &
+					 ~ATA_EH_PERDEV_MASK;
+			ehc->i.dev_action[dev->devno] &= ATA_EH_PERDEV_MASK;
+
+			/* process hotplug request */
+			if (dev->flags & ATA_DFLAG_DETACH)
+				ata_eh_detach_dev(dev);
+
+			/* schedule probe if necessary */
+			if (!ata_dev_enabled(dev))
+				ata_eh_schedule_probe(dev);
+		}
+	}
+
+ retry:
+	rc = 0;
+
+	/* if UNLOADING, finish immediately */
+	if (ap->pflags & ATA_PFLAG_UNLOADING)
+		goto out;
+
+	/* prep for EH */
+	ata_for_each_link(link, ap, EDGE) {
+		struct ata_eh_context *ehc = &link->eh_context;
+
+		/* skip EH if possible. */
+		if (ata_eh_skip_recovery(link))
+			ehc->i.action = 0;
+
+		ata_for_each_dev(dev, link, ALL)
+			ehc->classes[dev->devno] = ATA_DEV_UNKNOWN;
+	}
+
+	/* reset */
+	ata_for_each_link(link, ap, EDGE) {
+		struct ata_eh_context *ehc = &link->eh_context;
+
+		if (!(ehc->i.action & ATA_EH_RESET))
+			continue;
+
+		rc = ata_eh_reset(link, ata_link_nr_vacant(link),
+				  prereset, softreset, hardreset, postreset);
+		if (rc) {
+			ata_link_err(link, "reset failed, giving up\n");
+			goto out;
+		}
+	}
+
+	do {
+		unsigned long now;
+
+		/*
+		 * clears ATA_EH_PARK in eh_info and resets
+		 * ap->park_req_pending
+		 */
+		ata_eh_pull_park_action(ap);
+
+		deadline = jiffies;
+		ata_for_each_link(link, ap, EDGE) {
+			ata_for_each_dev(dev, link, ALL) {
+				struct ata_eh_context *ehc = &link->eh_context;
+				unsigned long tmp;
+
+				if (dev->class != ATA_DEV_ATA &&
+				    dev->class != ATA_DEV_ZAC)
+					continue;
+				if (!(ehc->i.dev_action[dev->devno] &
+				      ATA_EH_PARK))
+					continue;
+				tmp = dev->unpark_deadline;
+				if (time_before(deadline, tmp))
+					deadline = tmp;
+				else if (time_before_eq(tmp, jiffies))
+					continue;
+				if (ehc->unloaded_mask & (1 << dev->devno))
+					continue;
+
+				ata_eh_park_issue_cmd(dev, 1);
+			}
+		}
+
+		now = jiffies;
+		if (time_before_eq(deadline, now))
+			break;
+
+		ata_eh_release(ap);
+		deadline = wait_for_completion_timeout(&ap->park_req_pending,
+						       deadline - now);
+		ata_eh_acquire(ap);
+	} while (deadline);
+	ata_for_each_link(link, ap, EDGE) {
+		ata_for_each_dev(dev, link, ALL) {
+			if (!(link->eh_context.unloaded_mask &
+			      (1 << dev->devno)))
+				continue;
+
+			ata_eh_park_issue_cmd(dev, 0);
+			ata_eh_done(link, dev, ATA_EH_PARK);
+		}
+	}
+
+	/* the rest */
+	nr_fails = 0;
+	ata_for_each_link(link, ap, PMP_FIRST) {
+		struct ata_eh_context *ehc = &link->eh_context;
+
+		if (sata_pmp_attached(ap) && ata_is_host_link(link))
+			goto config_lpm;
+
+		/* revalidate existing devices and attach new ones */
+		rc = ata_eh_revalidate_and_attach(link, &dev);
+		if (rc)
+			goto rest_fail;
+
+		/* if PMP got attached, return, pmp EH will take care of it */
+		if (link->device->class == ATA_DEV_PMP) {
+			ehc->i.action = 0;
+			return 0;
+		}
+
+		/* configure transfer mode if necessary */
+		if (ehc->i.flags & ATA_EHI_SETMODE) {
+			rc = ata_set_mode(link, &dev);
+			if (rc)
+				goto rest_fail;
+			ehc->i.flags &= ~ATA_EHI_SETMODE;
+		}
+
+		/* If reset has been issued, clear UA to avoid
+		 * disrupting the current users of the device.
+		 */
+		if (ehc->i.flags & ATA_EHI_DID_RESET) {
+			ata_for_each_dev(dev, link, ALL) {
+				if (dev->class != ATA_DEV_ATAPI)
+					continue;
+				rc = atapi_eh_clear_ua(dev);
+				if (rc)
+					goto rest_fail;
+				if (zpodd_dev_enabled(dev))
+					zpodd_post_poweron(dev);
+			}
+		}
+
+		/* retry flush if necessary */
+		ata_for_each_dev(dev, link, ALL) {
+			if (dev->class != ATA_DEV_ATA &&
+			    dev->class != ATA_DEV_ZAC)
+				continue;
+			rc = ata_eh_maybe_retry_flush(dev);
+			if (rc)
+				goto rest_fail;
+		}
+
+	config_lpm:
+		/* configure link power saving */
+		if (link->lpm_policy != ap->target_lpm_policy) {
+			rc = ata_eh_set_lpm(link, ap->target_lpm_policy, &dev);
+			if (rc)
+				goto rest_fail;
+		}
+
+		/* this link is okay now */
+		ehc->i.flags = 0;
+		continue;
+
+	rest_fail:
+		nr_fails++;
+		if (dev)
+			ata_eh_handle_dev_fail(dev, rc);
+
+		if (ap->pflags & ATA_PFLAG_FROZEN) {
+			/* PMP reset requires working host port.
+			 * Can't retry if it's frozen.
+			 */
+			if (sata_pmp_attached(ap))
+				goto out;
+			break;
+		}
+	}
+
+	if (nr_fails)
+		goto retry;
+
+ out:
+	if (rc && r_failed_link)
+		*r_failed_link = link;
+
+	DPRINTK("EXIT, rc=%d\n", rc);
+	return rc;
+}
+
+/**
+ *	ata_eh_finish - finish up EH
+ *	@ap: host port to finish EH for
+ *
+ *	Recovery is complete.  Clean up EH states and retry or finish
+ *	failed qcs.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_eh_finish(struct ata_port *ap)
+{
+	int tag;
+
+	/* retry or finish qcs */
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED))
+			continue;
+
+		if (qc->err_mask) {
+			/* FIXME: Once EH migration is complete,
+			 * generate sense data in this function,
+			 * considering both err_mask and tf.
+			 */
+			if (qc->flags & ATA_QCFLAG_RETRY)
+				ata_eh_qc_retry(qc);
+			else
+				ata_eh_qc_complete(qc);
+		} else {
+			if (qc->flags & ATA_QCFLAG_SENSE_VALID) {
+				ata_eh_qc_complete(qc);
+			} else {
+				/* feed zero TF to sense generation */
+				memset(&qc->result_tf, 0, sizeof(qc->result_tf));
+				ata_eh_qc_retry(qc);
+			}
+		}
+	}
+
+	/* make sure nr_active_links is zero after EH */
+	WARN_ON(ap->nr_active_links);
+	ap->nr_active_links = 0;
+}
+
+/**
+ *	ata_do_eh - do standard error handling
+ *	@ap: host port to handle error for
+ *
+ *	@prereset: prereset method (can be NULL)
+ *	@softreset: softreset method (can be NULL)
+ *	@hardreset: hardreset method (can be NULL)
+ *	@postreset: postreset method (can be NULL)
+ *
+ *	Perform standard error handling sequence.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+void ata_do_eh(struct ata_port *ap, ata_prereset_fn_t prereset,
+	       ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
+	       ata_postreset_fn_t postreset)
+{
+	struct ata_device *dev;
+	int rc;
+
+	ata_eh_autopsy(ap);
+	ata_eh_report(ap);
+
+	rc = ata_eh_recover(ap, prereset, softreset, hardreset, postreset,
+			    NULL);
+	if (rc) {
+		ata_for_each_dev(dev, &ap->link, ALL)
+			ata_dev_disable(dev);
+	}
+
+	ata_eh_finish(ap);
+}
+
+/**
+ *	ata_std_error_handler - standard error handler
+ *	@ap: host port to handle error for
+ *
+ *	Standard error handler
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+void ata_std_error_handler(struct ata_port *ap)
+{
+	struct ata_port_operations *ops = ap->ops;
+	ata_reset_fn_t hardreset = ops->hardreset;
+
+	/* ignore built-in hardreset if SCR access is not available */
+	if (hardreset == sata_std_hardreset && !sata_scr_valid(&ap->link))
+		hardreset = NULL;
+
+	ata_do_eh(ap, ops->prereset, ops->softreset, hardreset, ops->postreset);
+}
+
+#ifdef CONFIG_PM
+/**
+ *	ata_eh_handle_port_suspend - perform port suspend operation
+ *	@ap: port to suspend
+ *
+ *	Suspend @ap.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+static void ata_eh_handle_port_suspend(struct ata_port *ap)
+{
+	unsigned long flags;
+	int rc = 0;
+	struct ata_device *dev;
+
+	/* are we suspending? */
+	spin_lock_irqsave(ap->lock, flags);
+	if (!(ap->pflags & ATA_PFLAG_PM_PENDING) ||
+	    ap->pm_mesg.event & PM_EVENT_RESUME) {
+		spin_unlock_irqrestore(ap->lock, flags);
+		return;
+	}
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	WARN_ON(ap->pflags & ATA_PFLAG_SUSPENDED);
+
+	/*
+	 * If we have a ZPODD attached, check its zero
+	 * power ready status before the port is frozen.
+	 * Only needed for runtime suspend.
+	 */
+	if (PMSG_IS_AUTO(ap->pm_mesg)) {
+		ata_for_each_dev(dev, &ap->link, ENABLED) {
+			if (zpodd_dev_enabled(dev))
+				zpodd_on_suspend(dev);
+		}
+	}
+
+	/* tell ACPI we're suspending */
+	rc = ata_acpi_on_suspend(ap);
+	if (rc)
+		goto out;
+
+	/* suspend */
+	ata_eh_freeze_port(ap);
+
+	if (ap->ops->port_suspend)
+		rc = ap->ops->port_suspend(ap, ap->pm_mesg);
+
+	ata_acpi_set_state(ap, ap->pm_mesg);
+ out:
+	/* update the flags */
+	spin_lock_irqsave(ap->lock, flags);
+
+	ap->pflags &= ~ATA_PFLAG_PM_PENDING;
+	if (rc == 0)
+		ap->pflags |= ATA_PFLAG_SUSPENDED;
+	else if (ap->pflags & ATA_PFLAG_FROZEN)
+		ata_port_schedule_eh(ap);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	return;
+}
+
+/**
+ *	ata_eh_handle_port_resume - perform port resume operation
+ *	@ap: port to resume
+ *
+ *	Resume @ap.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+static void ata_eh_handle_port_resume(struct ata_port *ap)
+{
+	struct ata_link *link;
+	struct ata_device *dev;
+	unsigned long flags;
+	int rc = 0;
+
+	/* are we resuming? */
+	spin_lock_irqsave(ap->lock, flags);
+	if (!(ap->pflags & ATA_PFLAG_PM_PENDING) ||
+	    !(ap->pm_mesg.event & PM_EVENT_RESUME)) {
+		spin_unlock_irqrestore(ap->lock, flags);
+		return;
+	}
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	WARN_ON(!(ap->pflags & ATA_PFLAG_SUSPENDED));
+
+	/*
+	 * Error timestamps are in jiffies which doesn't run while
+	 * suspended and PHY events during resume isn't too uncommon.
+	 * When the two are combined, it can lead to unnecessary speed
+	 * downs if the machine is suspended and resumed repeatedly.
+	 * Clear error history.
+	 */
+	ata_for_each_link(link, ap, HOST_FIRST)
+		ata_for_each_dev(dev, link, ALL)
+			ata_ering_clear(&dev->ering);
+
+	ata_acpi_set_state(ap, ap->pm_mesg);
+
+	if (ap->ops->port_resume)
+		rc = ap->ops->port_resume(ap);
+
+	/* tell ACPI that we're resuming */
+	ata_acpi_on_resume(ap);
+
+	/* update the flags */
+	spin_lock_irqsave(ap->lock, flags);
+	ap->pflags &= ~(ATA_PFLAG_PM_PENDING | ATA_PFLAG_SUSPENDED);
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+#endif /* CONFIG_PM */