diff options
Diffstat (limited to 'drivers/usb/host/ehci-q.c')
| -rw-r--r-- | drivers/usb/host/ehci-q.c | 1476 |
1 files changed, 1476 insertions, 0 deletions
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c new file mode 100644 index 000000000..54f5332f8 --- /dev/null +++ b/drivers/usb/host/ehci-q.c @@ -0,0 +1,1476 @@ +/* + * Copyright (C) 2001-2004 by David Brownell + * + * 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 of the License, 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; if not, write to the Free Software Foundation, + * Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +/* this file is part of ehci-hcd.c */ + +/*-------------------------------------------------------------------------*/ + +/* + * EHCI hardware queue manipulation ... the core. QH/QTD manipulation. + * + * Control, bulk, and interrupt traffic all use "qh" lists. They list "qtd" + * entries describing USB transactions, max 16-20kB/entry (with 4kB-aligned + * buffers needed for the larger number). We use one QH per endpoint, queue + * multiple urbs (all three types) per endpoint. URBs may need several qtds. + * + * ISO traffic uses "ISO TD" (itd, and sitd) records, and (along with + * interrupts) needs careful scheduling. Performance improvements can be + * an ongoing challenge. That's in "ehci-sched.c". + * + * USB 1.1 devices are handled (a) by "companion" OHCI or UHCI root hubs, + * or otherwise through transaction translators (TTs) in USB 2.0 hubs using + * (b) special fields in qh entries or (c) split iso entries. TTs will + * buffer low/full speed data so the host collects it at high speed. + */ + +/*-------------------------------------------------------------------------*/ + +/* fill a qtd, returning how much of the buffer we were able to queue up */ + +static int +qtd_fill(struct ehci_hcd *ehci, struct ehci_qtd *qtd, dma_addr_t buf, + size_t len, int token, int maxpacket) +{ + int i, count; + u64 addr = buf; + + /* one buffer entry per 4K ... first might be short or unaligned */ + qtd->hw_buf[0] = cpu_to_hc32(ehci, (u32)addr); + qtd->hw_buf_hi[0] = cpu_to_hc32(ehci, (u32)(addr >> 32)); + count = 0x1000 - (buf & 0x0fff); /* rest of that page */ + if (likely (len < count)) /* ... iff needed */ + count = len; + else { + buf += 0x1000; + buf &= ~0x0fff; + + /* per-qtd limit: from 16K to 20K (best alignment) */ + for (i = 1; count < len && i < 5; i++) { + addr = buf; + qtd->hw_buf[i] = cpu_to_hc32(ehci, (u32)addr); + qtd->hw_buf_hi[i] = cpu_to_hc32(ehci, + (u32)(addr >> 32)); + buf += 0x1000; + if ((count + 0x1000) < len) + count += 0x1000; + else + count = len; + } + + /* short packets may only terminate transfers */ + if (count != len) + count -= (count % maxpacket); + } + qtd->hw_token = cpu_to_hc32(ehci, (count << 16) | token); + qtd->length = count; + + return count; +} + +/*-------------------------------------------------------------------------*/ + +static inline void +qh_update (struct ehci_hcd *ehci, struct ehci_qh *qh, struct ehci_qtd *qtd) +{ + struct ehci_qh_hw *hw = qh->hw; + + /* writes to an active overlay are unsafe */ + WARN_ON(qh->qh_state != QH_STATE_IDLE); + + hw->hw_qtd_next = QTD_NEXT(ehci, qtd->qtd_dma); + hw->hw_alt_next = EHCI_LIST_END(ehci); + + /* Except for control endpoints, we make hardware maintain data + * toggle (like OHCI) ... here (re)initialize the toggle in the QH, + * and set the pseudo-toggle in udev. Only usb_clear_halt() will + * ever clear it. + */ + if (!(hw->hw_info1 & cpu_to_hc32(ehci, QH_TOGGLE_CTL))) { + unsigned is_out, epnum; + + is_out = qh->is_out; + epnum = (hc32_to_cpup(ehci, &hw->hw_info1) >> 8) & 0x0f; + if (unlikely(!usb_gettoggle(qh->ps.udev, epnum, is_out))) { + hw->hw_token &= ~cpu_to_hc32(ehci, QTD_TOGGLE); + usb_settoggle(qh->ps.udev, epnum, is_out, 1); + } + } + + hw->hw_token &= cpu_to_hc32(ehci, QTD_TOGGLE | QTD_STS_PING); +} + +/* if it weren't for a common silicon quirk (writing the dummy into the qh + * overlay, so qh->hw_token wrongly becomes inactive/halted), only fault + * recovery (including urb dequeue) would need software changes to a QH... + */ +static void +qh_refresh (struct ehci_hcd *ehci, struct ehci_qh *qh) +{ + struct ehci_qtd *qtd; + + qtd = list_entry(qh->qtd_list.next, struct ehci_qtd, qtd_list); + + /* + * first qtd may already be partially processed. + * If we come here during unlink, the QH overlay region + * might have reference to the just unlinked qtd. The + * qtd is updated in qh_completions(). Update the QH + * overlay here. + */ + if (qh->hw->hw_token & ACTIVE_BIT(ehci)) + qh->hw->hw_qtd_next = qtd->hw_next; + else + qh_update(ehci, qh, qtd); +} + +/*-------------------------------------------------------------------------*/ + +static void qh_link_async(struct ehci_hcd *ehci, struct ehci_qh *qh); + +static void ehci_clear_tt_buffer_complete(struct usb_hcd *hcd, + struct usb_host_endpoint *ep) +{ + struct ehci_hcd *ehci = hcd_to_ehci(hcd); + struct ehci_qh *qh = ep->hcpriv; + unsigned long flags; + + spin_lock_irqsave(&ehci->lock, flags); + qh->clearing_tt = 0; + if (qh->qh_state == QH_STATE_IDLE && !list_empty(&qh->qtd_list) + && ehci->rh_state == EHCI_RH_RUNNING) + qh_link_async(ehci, qh); + spin_unlock_irqrestore(&ehci->lock, flags); +} + +static void ehci_clear_tt_buffer(struct ehci_hcd *ehci, struct ehci_qh *qh, + struct urb *urb, u32 token) +{ + + /* If an async split transaction gets an error or is unlinked, + * the TT buffer may be left in an indeterminate state. We + * have to clear the TT buffer. + * + * Note: this routine is never called for Isochronous transfers. + */ + if (urb->dev->tt && !usb_pipeint(urb->pipe) && !qh->clearing_tt) { +#ifdef CONFIG_DYNAMIC_DEBUG + struct usb_device *tt = urb->dev->tt->hub; + dev_dbg(&tt->dev, + "clear tt buffer port %d, a%d ep%d t%08x\n", + urb->dev->ttport, urb->dev->devnum, + usb_pipeendpoint(urb->pipe), token); +#endif /* CONFIG_DYNAMIC_DEBUG */ + if (!ehci_is_TDI(ehci) + || urb->dev->tt->hub != + ehci_to_hcd(ehci)->self.root_hub) { + if (usb_hub_clear_tt_buffer(urb) == 0) + qh->clearing_tt = 1; + } else { + + /* REVISIT ARC-derived cores don't clear the root + * hub TT buffer in this way... + */ + } + } +} + +static int qtd_copy_status ( + struct ehci_hcd *ehci, + struct urb *urb, + size_t length, + u32 token +) +{ + int status = -EINPROGRESS; + + /* count IN/OUT bytes, not SETUP (even short packets) */ + if (likely (QTD_PID (token) != 2)) + urb->actual_length += length - QTD_LENGTH (token); + + /* don't modify error codes */ + if (unlikely(urb->unlinked)) + return status; + + /* force cleanup after short read; not always an error */ + if (unlikely (IS_SHORT_READ (token))) + status = -EREMOTEIO; + + /* serious "can't proceed" faults reported by the hardware */ + if (token & QTD_STS_HALT) { + if (token & QTD_STS_BABBLE) { + /* FIXME "must" disable babbling device's port too */ + status = -EOVERFLOW; + /* CERR nonzero + halt --> stall */ + } else if (QTD_CERR(token)) { + status = -EPIPE; + + /* In theory, more than one of the following bits can be set + * since they are sticky and the transaction is retried. + * Which to test first is rather arbitrary. + */ + } else if (token & QTD_STS_MMF) { + /* fs/ls interrupt xfer missed the complete-split */ + status = -EPROTO; + } else if (token & QTD_STS_DBE) { + status = (QTD_PID (token) == 1) /* IN ? */ + ? -ENOSR /* hc couldn't read data */ + : -ECOMM; /* hc couldn't write data */ + } else if (token & QTD_STS_XACT) { + /* timeout, bad CRC, wrong PID, etc */ + ehci_dbg(ehci, "devpath %s ep%d%s 3strikes\n", + urb->dev->devpath, + usb_pipeendpoint(urb->pipe), + usb_pipein(urb->pipe) ? "in" : "out"); + status = -EPROTO; + } else { /* unknown */ + status = -EPROTO; + } + } + + return status; +} + +static void +ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status) +{ + if (usb_pipetype(urb->pipe) == PIPE_INTERRUPT) { + /* ... update hc-wide periodic stats */ + ehci_to_hcd(ehci)->self.bandwidth_int_reqs--; + } + + if (unlikely(urb->unlinked)) { + COUNT(ehci->stats.unlink); + } else { + /* report non-error and short read status as zero */ + if (status == -EINPROGRESS || status == -EREMOTEIO) + status = 0; + COUNT(ehci->stats.complete); + } + +#ifdef EHCI_URB_TRACE + ehci_dbg (ehci, + "%s %s urb %p ep%d%s status %d len %d/%d\n", + __func__, urb->dev->devpath, urb, + usb_pipeendpoint (urb->pipe), + usb_pipein (urb->pipe) ? "in" : "out", + status, + urb->actual_length, urb->transfer_buffer_length); +#endif + + usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb); + usb_hcd_giveback_urb(ehci_to_hcd(ehci), urb, status); +} + +static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh); + +/* + * Process and free completed qtds for a qh, returning URBs to drivers. + * Chases up to qh->hw_current. Returns nonzero if the caller should + * unlink qh. + */ +static unsigned +qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh) +{ + struct ehci_qtd *last, *end = qh->dummy; + struct list_head *entry, *tmp; + int last_status; + int stopped; + u8 state; + struct ehci_qh_hw *hw = qh->hw; + + /* completions (or tasks on other cpus) must never clobber HALT + * till we've gone through and cleaned everything up, even when + * they add urbs to this qh's queue or mark them for unlinking. + * + * NOTE: unlinking expects to be done in queue order. + * + * It's a bug for qh->qh_state to be anything other than + * QH_STATE_IDLE, unless our caller is scan_async() or + * scan_intr(). + */ + state = qh->qh_state; + qh->qh_state = QH_STATE_COMPLETING; + stopped = (state == QH_STATE_IDLE); + + rescan: + last = NULL; + last_status = -EINPROGRESS; + qh->dequeue_during_giveback = 0; + + /* remove de-activated QTDs from front of queue. + * after faults (including short reads), cleanup this urb + * then let the queue advance. + * if queue is stopped, handles unlinks. + */ + list_for_each_safe (entry, tmp, &qh->qtd_list) { + struct ehci_qtd *qtd; + struct urb *urb; + u32 token = 0; + + qtd = list_entry (entry, struct ehci_qtd, qtd_list); + urb = qtd->urb; + + /* clean up any state from previous QTD ...*/ + if (last) { + if (likely (last->urb != urb)) { + ehci_urb_done(ehci, last->urb, last_status); + last_status = -EINPROGRESS; + } + ehci_qtd_free (ehci, last); + last = NULL; + } + + /* ignore urbs submitted during completions we reported */ + if (qtd == end) + break; + + /* hardware copies qtd out of qh overlay */ + rmb (); + token = hc32_to_cpu(ehci, qtd->hw_token); + + /* always clean up qtds the hc de-activated */ + retry_xacterr: + if ((token & QTD_STS_ACTIVE) == 0) { + + /* Report Data Buffer Error: non-fatal but useful */ + if (token & QTD_STS_DBE) + ehci_dbg(ehci, + "detected DataBufferErr for urb %p ep%d%s len %d, qtd %p [qh %p]\n", + urb, + usb_endpoint_num(&urb->ep->desc), + usb_endpoint_dir_in(&urb->ep->desc) ? "in" : "out", + urb->transfer_buffer_length, + qtd, + qh); + + /* on STALL, error, and short reads this urb must + * complete and all its qtds must be recycled. + */ + if ((token & QTD_STS_HALT) != 0) { + + /* retry transaction errors until we + * reach the software xacterr limit + */ + if ((token & QTD_STS_XACT) && + QTD_CERR(token) == 0 && + ++qh->xacterrs < QH_XACTERR_MAX && + !urb->unlinked) { + ehci_dbg(ehci, + "detected XactErr len %zu/%zu retry %d\n", + qtd->length - QTD_LENGTH(token), qtd->length, qh->xacterrs); + + /* reset the token in the qtd and the + * qh overlay (which still contains + * the qtd) so that we pick up from + * where we left off + */ + token &= ~QTD_STS_HALT; + token |= QTD_STS_ACTIVE | + (EHCI_TUNE_CERR << 10); + qtd->hw_token = cpu_to_hc32(ehci, + token); + wmb(); + hw->hw_token = cpu_to_hc32(ehci, + token); + goto retry_xacterr; + } + stopped = 1; + + /* magic dummy for some short reads; qh won't advance. + * that silicon quirk can kick in with this dummy too. + * + * other short reads won't stop the queue, including + * control transfers (status stage handles that) or + * most other single-qtd reads ... the queue stops if + * URB_SHORT_NOT_OK was set so the driver submitting + * the urbs could clean it up. + */ + } else if (IS_SHORT_READ (token) + && !(qtd->hw_alt_next + & EHCI_LIST_END(ehci))) { + stopped = 1; + } + + /* stop scanning when we reach qtds the hc is using */ + } else if (likely (!stopped + && ehci->rh_state >= EHCI_RH_RUNNING)) { + break; + + /* scan the whole queue for unlinks whenever it stops */ + } else { + stopped = 1; + + /* cancel everything if we halt, suspend, etc */ + if (ehci->rh_state < EHCI_RH_RUNNING) + last_status = -ESHUTDOWN; + + /* this qtd is active; skip it unless a previous qtd + * for its urb faulted, or its urb was canceled. + */ + else if (last_status == -EINPROGRESS && !urb->unlinked) + continue; + + /* + * If this was the active qtd when the qh was unlinked + * and the overlay's token is active, then the overlay + * hasn't been written back to the qtd yet so use its + * token instead of the qtd's. After the qtd is + * processed and removed, the overlay won't be valid + * any more. + */ + if (state == QH_STATE_IDLE && + qh->qtd_list.next == &qtd->qtd_list && + (hw->hw_token & ACTIVE_BIT(ehci))) { + token = hc32_to_cpu(ehci, hw->hw_token); + hw->hw_token &= ~ACTIVE_BIT(ehci); + + /* An unlink may leave an incomplete + * async transaction in the TT buffer. + * We have to clear it. + */ + ehci_clear_tt_buffer(ehci, qh, urb, token); + } + } + + /* unless we already know the urb's status, collect qtd status + * and update count of bytes transferred. in common short read + * cases with only one data qtd (including control transfers), + * queue processing won't halt. but with two or more qtds (for + * example, with a 32 KB transfer), when the first qtd gets a + * short read the second must be removed by hand. + */ + if (last_status == -EINPROGRESS) { + last_status = qtd_copy_status(ehci, urb, + qtd->length, token); + if (last_status == -EREMOTEIO + && (qtd->hw_alt_next + & EHCI_LIST_END(ehci))) + last_status = -EINPROGRESS; + + /* As part of low/full-speed endpoint-halt processing + * we must clear the TT buffer (11.17.5). + */ + if (unlikely(last_status != -EINPROGRESS && + last_status != -EREMOTEIO)) { + /* The TT's in some hubs malfunction when they + * receive this request following a STALL (they + * stop sending isochronous packets). Since a + * STALL can't leave the TT buffer in a busy + * state (if you believe Figures 11-48 - 11-51 + * in the USB 2.0 spec), we won't clear the TT + * buffer in this case. Strictly speaking this + * is a violation of the spec. + */ + if (last_status != -EPIPE) + ehci_clear_tt_buffer(ehci, qh, urb, + token); + } + } + + /* if we're removing something not at the queue head, + * patch the hardware queue pointer. + */ + if (stopped && qtd->qtd_list.prev != &qh->qtd_list) { + last = list_entry (qtd->qtd_list.prev, + struct ehci_qtd, qtd_list); + last->hw_next = qtd->hw_next; + } + + /* remove qtd; it's recycled after possible urb completion */ + list_del (&qtd->qtd_list); + last = qtd; + + /* reinit the xacterr counter for the next qtd */ + qh->xacterrs = 0; + } + + /* last urb's completion might still need calling */ + if (likely (last != NULL)) { + ehci_urb_done(ehci, last->urb, last_status); + ehci_qtd_free (ehci, last); + } + + /* Do we need to rescan for URBs dequeued during a giveback? */ + if (unlikely(qh->dequeue_during_giveback)) { + /* If the QH is already unlinked, do the rescan now. */ + if (state == QH_STATE_IDLE) + goto rescan; + + /* Otherwise the caller must unlink the QH. */ + } + + /* restore original state; caller must unlink or relink */ + qh->qh_state = state; + + /* be sure the hardware's done with the qh before refreshing + * it after fault cleanup, or recovering from silicon wrongly + * overlaying the dummy qtd (which reduces DMA chatter). + * + * We won't refresh a QH that's linked (after the HC + * stopped the queue). That avoids a race: + * - HC reads first part of QH; + * - CPU updates that first part and the token; + * - HC reads rest of that QH, including token + * Result: HC gets an inconsistent image, and then + * DMAs to/from the wrong memory (corrupting it). + * + * That should be rare for interrupt transfers, + * except maybe high bandwidth ... + */ + if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci)) + qh->exception = 1; + + /* Let the caller know if the QH needs to be unlinked. */ + return qh->exception; +} + +/*-------------------------------------------------------------------------*/ + +// high bandwidth multiplier, as encoded in highspeed endpoint descriptors +#define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03)) +// ... and packet size, for any kind of endpoint descriptor +#define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff) + +/* + * reverse of qh_urb_transaction: free a list of TDs. + * used for cleanup after errors, before HC sees an URB's TDs. + */ +static void qtd_list_free ( + struct ehci_hcd *ehci, + struct urb *urb, + struct list_head *qtd_list +) { + struct list_head *entry, *temp; + + list_for_each_safe (entry, temp, qtd_list) { + struct ehci_qtd *qtd; + + qtd = list_entry (entry, struct ehci_qtd, qtd_list); + list_del (&qtd->qtd_list); + ehci_qtd_free (ehci, qtd); + } +} + +/* + * create a list of filled qtds for this URB; won't link into qh. + */ +static struct list_head * +qh_urb_transaction ( + struct ehci_hcd *ehci, + struct urb *urb, + struct list_head *head, + gfp_t flags +) { + struct ehci_qtd *qtd, *qtd_prev; + dma_addr_t buf; + int len, this_sg_len, maxpacket; + int is_input; + u32 token; + int i; + struct scatterlist *sg; + + /* + * URBs map to sequences of QTDs: one logical transaction + */ + qtd = ehci_qtd_alloc (ehci, flags); + if (unlikely (!qtd)) + return NULL; + list_add_tail (&qtd->qtd_list, head); + qtd->urb = urb; + + token = QTD_STS_ACTIVE; + token |= (EHCI_TUNE_CERR << 10); + /* for split transactions, SplitXState initialized to zero */ + + len = urb->transfer_buffer_length; + is_input = usb_pipein (urb->pipe); + if (usb_pipecontrol (urb->pipe)) { + /* SETUP pid */ + qtd_fill(ehci, qtd, urb->setup_dma, + sizeof (struct usb_ctrlrequest), + token | (2 /* "setup" */ << 8), 8); + + /* ... and always at least one more pid */ + token ^= QTD_TOGGLE; + qtd_prev = qtd; + qtd = ehci_qtd_alloc (ehci, flags); + if (unlikely (!qtd)) + goto cleanup; + qtd->urb = urb; + qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma); + list_add_tail (&qtd->qtd_list, head); + + /* for zero length DATA stages, STATUS is always IN */ + if (len == 0) + token |= (1 /* "in" */ << 8); + } + + /* + * data transfer stage: buffer setup + */ + i = urb->num_mapped_sgs; + if (len > 0 && i > 0) { + sg = urb->sg; + buf = sg_dma_address(sg); + + /* urb->transfer_buffer_length may be smaller than the + * size of the scatterlist (or vice versa) + */ + this_sg_len = min_t(int, sg_dma_len(sg), len); + } else { + sg = NULL; + buf = urb->transfer_dma; + this_sg_len = len; + } + + if (is_input) + token |= (1 /* "in" */ << 8); + /* else it's already initted to "out" pid (0 << 8) */ + + maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input)); + + /* + * buffer gets wrapped in one or more qtds; + * last one may be "short" (including zero len) + * and may serve as a control status ack + */ + for (;;) { + int this_qtd_len; + + this_qtd_len = qtd_fill(ehci, qtd, buf, this_sg_len, token, + maxpacket); + this_sg_len -= this_qtd_len; + len -= this_qtd_len; + buf += this_qtd_len; + + /* + * short reads advance to a "magic" dummy instead of the next + * qtd ... that forces the queue to stop, for manual cleanup. + * (this will usually be overridden later.) + */ + if (is_input) + qtd->hw_alt_next = ehci->async->hw->hw_alt_next; + + /* qh makes control packets use qtd toggle; maybe switch it */ + if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0) + token ^= QTD_TOGGLE; + + if (likely(this_sg_len <= 0)) { + if (--i <= 0 || len <= 0) + break; + sg = sg_next(sg); + buf = sg_dma_address(sg); + this_sg_len = min_t(int, sg_dma_len(sg), len); + } + + qtd_prev = qtd; + qtd = ehci_qtd_alloc (ehci, flags); + if (unlikely (!qtd)) + goto cleanup; + qtd->urb = urb; + qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma); + list_add_tail (&qtd->qtd_list, head); + } + + /* + * unless the caller requires manual cleanup after short reads, + * have the alt_next mechanism keep the queue running after the + * last data qtd (the only one, for control and most other cases). + */ + if (likely ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0 + || usb_pipecontrol (urb->pipe))) + qtd->hw_alt_next = EHCI_LIST_END(ehci); + + /* + * control requests may need a terminating data "status" ack; + * other OUT ones may need a terminating short packet + * (zero length). + */ + if (likely (urb->transfer_buffer_length != 0)) { + int one_more = 0; + + if (usb_pipecontrol (urb->pipe)) { + one_more = 1; + token ^= 0x0100; /* "in" <--> "out" */ + token |= QTD_TOGGLE; /* force DATA1 */ + } else if (usb_pipeout(urb->pipe) + && (urb->transfer_flags & URB_ZERO_PACKET) + && !(urb->transfer_buffer_length % maxpacket)) { + one_more = 1; + } + if (one_more) { + qtd_prev = qtd; + qtd = ehci_qtd_alloc (ehci, flags); + if (unlikely (!qtd)) + goto cleanup; + qtd->urb = urb; + qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma); + list_add_tail (&qtd->qtd_list, head); + + /* never any data in such packets */ + qtd_fill(ehci, qtd, 0, 0, token, 0); + } + } + + /* by default, enable interrupt on urb completion */ + if (likely (!(urb->transfer_flags & URB_NO_INTERRUPT))) + qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC); + return head; + +cleanup: + qtd_list_free (ehci, urb, head); + return NULL; +} + +/*-------------------------------------------------------------------------*/ + +// Would be best to create all qh's from config descriptors, +// when each interface/altsetting is established. Unlink +// any previous qh and cancel its urbs first; endpoints are +// implicitly reset then (data toggle too). +// That'd mean updating how usbcore talks to HCDs. (2.7?) + + +/* + * Each QH holds a qtd list; a QH is used for everything except iso. + * + * For interrupt urbs, the scheduler must set the microframe scheduling + * mask(s) each time the QH gets scheduled. For highspeed, that's + * just one microframe in the s-mask. For split interrupt transactions + * there are additional complications: c-mask, maybe FSTNs. + */ +static struct ehci_qh * +qh_make ( + struct ehci_hcd *ehci, + struct urb *urb, + gfp_t flags +) { + struct ehci_qh *qh = ehci_qh_alloc (ehci, flags); + u32 info1 = 0, info2 = 0; + int is_input, type; + int maxp = 0; + struct usb_tt *tt = urb->dev->tt; + struct ehci_qh_hw *hw; + + if (!qh) + return qh; + + /* + * init endpoint/device data for this QH + */ + info1 |= usb_pipeendpoint (urb->pipe) << 8; + info1 |= usb_pipedevice (urb->pipe) << 0; + + is_input = usb_pipein (urb->pipe); + type = usb_pipetype (urb->pipe); + maxp = usb_maxpacket (urb->dev, urb->pipe, !is_input); + + /* 1024 byte maxpacket is a hardware ceiling. High bandwidth + * acts like up to 3KB, but is built from smaller packets. + */ + if (max_packet(maxp) > 1024) { + ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp)); + goto done; + } + + /* Compute interrupt scheduling parameters just once, and save. + * - allowing for high bandwidth, how many nsec/uframe are used? + * - split transactions need a second CSPLIT uframe; same question + * - splits also need a schedule gap (for full/low speed I/O) + * - qh has a polling interval + * + * For control/bulk requests, the HC or TT handles these. + */ + if (type == PIPE_INTERRUPT) { + unsigned tmp; + + qh->ps.usecs = NS_TO_US(usb_calc_bus_time(USB_SPEED_HIGH, + is_input, 0, + hb_mult(maxp) * max_packet(maxp))); + qh->ps.phase = NO_FRAME; + + if (urb->dev->speed == USB_SPEED_HIGH) { + qh->ps.c_usecs = 0; + qh->gap_uf = 0; + + if (urb->interval > 1 && urb->interval < 8) { + /* NOTE interval 2 or 4 uframes could work. + * But interval 1 scheduling is simpler, and + * includes high bandwidth. + */ + urb->interval = 1; + } else if (urb->interval > ehci->periodic_size << 3) { + urb->interval = ehci->periodic_size << 3; + } + qh->ps.period = urb->interval >> 3; + + /* period for bandwidth allocation */ + tmp = min_t(unsigned, EHCI_BANDWIDTH_SIZE, + 1 << (urb->ep->desc.bInterval - 1)); + + /* Allow urb->interval to override */ + qh->ps.bw_uperiod = min_t(unsigned, tmp, urb->interval); + qh->ps.bw_period = qh->ps.bw_uperiod >> 3; + } else { + int think_time; + + /* gap is f(FS/LS transfer times) */ + qh->gap_uf = 1 + usb_calc_bus_time (urb->dev->speed, + is_input, 0, maxp) / (125 * 1000); + + /* FIXME this just approximates SPLIT/CSPLIT times */ + if (is_input) { // SPLIT, gap, CSPLIT+DATA + qh->ps.c_usecs = qh->ps.usecs + HS_USECS(0); + qh->ps.usecs = HS_USECS(1); + } else { // SPLIT+DATA, gap, CSPLIT + qh->ps.usecs += HS_USECS(1); + qh->ps.c_usecs = HS_USECS(0); + } + + think_time = tt ? tt->think_time : 0; + qh->ps.tt_usecs = NS_TO_US(think_time + + usb_calc_bus_time (urb->dev->speed, + is_input, 0, max_packet (maxp))); + if (urb->interval > ehci->periodic_size) + urb->interval = ehci->periodic_size; + qh->ps.period = urb->interval; + + /* period for bandwidth allocation */ + tmp = min_t(unsigned, EHCI_BANDWIDTH_FRAMES, + urb->ep->desc.bInterval); + tmp = rounddown_pow_of_two(tmp); + + /* Allow urb->interval to override */ + qh->ps.bw_period = min_t(unsigned, tmp, urb->interval); + qh->ps.bw_uperiod = qh->ps.bw_period << 3; + } + } + + /* support for tt scheduling, and access to toggles */ + qh->ps.udev = urb->dev; + qh->ps.ep = urb->ep; + + /* using TT? */ + switch (urb->dev->speed) { + case USB_SPEED_LOW: + info1 |= QH_LOW_SPEED; + /* FALL THROUGH */ + + case USB_SPEED_FULL: + /* EPS 0 means "full" */ + if (type != PIPE_INTERRUPT) + info1 |= (EHCI_TUNE_RL_TT << 28); + if (type == PIPE_CONTROL) { + info1 |= QH_CONTROL_EP; /* for TT */ + info1 |= QH_TOGGLE_CTL; /* toggle from qtd */ + } + info1 |= maxp << 16; + + info2 |= (EHCI_TUNE_MULT_TT << 30); + + /* Some Freescale processors have an erratum in which the + * port number in the queue head was 0..N-1 instead of 1..N. + */ + if (ehci_has_fsl_portno_bug(ehci)) + info2 |= (urb->dev->ttport-1) << 23; + else + info2 |= urb->dev->ttport << 23; + + /* set the address of the TT; for TDI's integrated + * root hub tt, leave it zeroed. + */ + if (tt && tt->hub != ehci_to_hcd(ehci)->self.root_hub) + info2 |= tt->hub->devnum << 16; + + /* NOTE: if (PIPE_INTERRUPT) { scheduler sets c-mask } */ + + break; + + case USB_SPEED_HIGH: /* no TT involved */ + info1 |= QH_HIGH_SPEED; + if (type == PIPE_CONTROL) { + info1 |= (EHCI_TUNE_RL_HS << 28); + info1 |= 64 << 16; /* usb2 fixed maxpacket */ + info1 |= QH_TOGGLE_CTL; /* toggle from qtd */ + info2 |= (EHCI_TUNE_MULT_HS << 30); + } else if (type == PIPE_BULK) { + info1 |= (EHCI_TUNE_RL_HS << 28); + /* The USB spec says that high speed bulk endpoints + * always use 512 byte maxpacket. But some device + * vendors decided to ignore that, and MSFT is happy + * to help them do so. So now people expect to use + * such nonconformant devices with Linux too; sigh. + */ + info1 |= max_packet(maxp) << 16; + info2 |= (EHCI_TUNE_MULT_HS << 30); + } else { /* PIPE_INTERRUPT */ + info1 |= max_packet (maxp) << 16; + info2 |= hb_mult (maxp) << 30; + } + break; + default: + ehci_dbg(ehci, "bogus dev %p speed %d\n", urb->dev, + urb->dev->speed); +done: + qh_destroy(ehci, qh); + return NULL; + } + + /* NOTE: if (PIPE_INTERRUPT) { scheduler sets s-mask } */ + + /* init as live, toggle clear */ + qh->qh_state = QH_STATE_IDLE; + hw = qh->hw; + hw->hw_info1 = cpu_to_hc32(ehci, info1); + hw->hw_info2 = cpu_to_hc32(ehci, info2); + qh->is_out = !is_input; + usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe), !is_input, 1); + return qh; +} + +/*-------------------------------------------------------------------------*/ + +static void enable_async(struct ehci_hcd *ehci) +{ + if (ehci->async_count++) + return; + + /* Stop waiting to turn off the async schedule */ + ehci->enabled_hrtimer_events &= ~BIT(EHCI_HRTIMER_DISABLE_ASYNC); + + /* Don't start the schedule until ASS is 0 */ + ehci_poll_ASS(ehci); + turn_on_io_watchdog(ehci); +} + +static void disable_async(struct ehci_hcd *ehci) +{ + if (--ehci->async_count) + return; + + /* The async schedule and unlink lists are supposed to be empty */ + WARN_ON(ehci->async->qh_next.qh || !list_empty(&ehci->async_unlink) || + !list_empty(&ehci->async_idle)); + + /* Don't turn off the schedule until ASS is 1 */ + ehci_poll_ASS(ehci); +} + +/* move qh (and its qtds) onto async queue; maybe enable queue. */ + +static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh) +{ + __hc32 dma = QH_NEXT(ehci, qh->qh_dma); + struct ehci_qh *head; + + /* Don't link a QH if there's a Clear-TT-Buffer pending */ + if (unlikely(qh->clearing_tt)) + return; + + WARN_ON(qh->qh_state != QH_STATE_IDLE); + + /* clear halt and/or toggle; and maybe recover from silicon quirk */ + qh_refresh(ehci, qh); + + /* splice right after start */ + head = ehci->async; + qh->qh_next = head->qh_next; + qh->hw->hw_next = head->hw->hw_next; + wmb (); + + head->qh_next.qh = qh; + head->hw->hw_next = dma; + + qh->qh_state = QH_STATE_LINKED; + qh->xacterrs = 0; + qh->exception = 0; + /* qtd completions reported later by interrupt */ + + enable_async(ehci); +} + +/*-------------------------------------------------------------------------*/ + +/* + * For control/bulk/interrupt, return QH with these TDs appended. + * Allocates and initializes the QH if necessary. + * Returns null if it can't allocate a QH it needs to. + * If the QH has TDs (urbs) already, that's great. + */ +static struct ehci_qh *qh_append_tds ( + struct ehci_hcd *ehci, + struct urb *urb, + struct list_head *qtd_list, + int epnum, + void **ptr +) +{ + struct ehci_qh *qh = NULL; + __hc32 qh_addr_mask = cpu_to_hc32(ehci, 0x7f); + + qh = (struct ehci_qh *) *ptr; + if (unlikely (qh == NULL)) { + /* can't sleep here, we have ehci->lock... */ + qh = qh_make (ehci, urb, GFP_ATOMIC); + *ptr = qh; + } + if (likely (qh != NULL)) { + struct ehci_qtd *qtd; + + if (unlikely (list_empty (qtd_list))) + qtd = NULL; + else + qtd = list_entry (qtd_list->next, struct ehci_qtd, + qtd_list); + + /* control qh may need patching ... */ + if (unlikely (epnum == 0)) { + + /* usb_reset_device() briefly reverts to address 0 */ + if (usb_pipedevice (urb->pipe) == 0) + qh->hw->hw_info1 &= ~qh_addr_mask; + } + + /* just one way to queue requests: swap with the dummy qtd. + * only hc or qh_refresh() ever modify the overlay. + */ + if (likely (qtd != NULL)) { + struct ehci_qtd *dummy; + dma_addr_t dma; + __hc32 token; + + /* to avoid racing the HC, use the dummy td instead of + * the first td of our list (becomes new dummy). both + * tds stay deactivated until we're done, when the + * HC is allowed to fetch the old dummy (4.10.2). + */ + token = qtd->hw_token; + qtd->hw_token = HALT_BIT(ehci); + + dummy = qh->dummy; + + dma = dummy->qtd_dma; + *dummy = *qtd; + dummy->qtd_dma = dma; + + list_del (&qtd->qtd_list); + list_add (&dummy->qtd_list, qtd_list); + list_splice_tail(qtd_list, &qh->qtd_list); + + ehci_qtd_init(ehci, qtd, qtd->qtd_dma); + qh->dummy = qtd; + + /* hc must see the new dummy at list end */ + dma = qtd->qtd_dma; + qtd = list_entry (qh->qtd_list.prev, + struct ehci_qtd, qtd_list); + qtd->hw_next = QTD_NEXT(ehci, dma); + + /* let the hc process these next qtds */ + wmb (); + dummy->hw_token = token; + + urb->hcpriv = qh; + } + } + return qh; +} + +/*-------------------------------------------------------------------------*/ + +static int +submit_async ( + struct ehci_hcd *ehci, + struct urb *urb, + struct list_head *qtd_list, + gfp_t mem_flags +) { + int epnum; + unsigned long flags; + struct ehci_qh *qh = NULL; + int rc; + + epnum = urb->ep->desc.bEndpointAddress; + +#ifdef EHCI_URB_TRACE + { + struct ehci_qtd *qtd; + qtd = list_entry(qtd_list->next, struct ehci_qtd, qtd_list); + ehci_dbg(ehci, + "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n", + __func__, urb->dev->devpath, urb, + epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out", + urb->transfer_buffer_length, + qtd, urb->ep->hcpriv); + } +#endif + + spin_lock_irqsave (&ehci->lock, flags); + if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) { + rc = -ESHUTDOWN; + goto done; + } + rc = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb); + if (unlikely(rc)) + goto done; + + qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv); + if (unlikely(qh == NULL)) { + usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb); + rc = -ENOMEM; + goto done; + } + + /* Control/bulk operations through TTs don't need scheduling, + * the HC and TT handle it when the TT has a buffer ready. + */ + if (likely (qh->qh_state == QH_STATE_IDLE)) + qh_link_async(ehci, qh); + done: + spin_unlock_irqrestore (&ehci->lock, flags); + if (unlikely (qh == NULL)) + qtd_list_free (ehci, urb, qtd_list); + return rc; +} + +/*-------------------------------------------------------------------------*/ +#ifdef CONFIG_USB_HCD_TEST_MODE +/* + * This function creates the qtds and submits them for the + * SINGLE_STEP_SET_FEATURE Test. + * This is done in two parts: first SETUP req for GetDesc is sent then + * 15 seconds later, the IN stage for GetDesc starts to req data from dev + * + * is_setup : i/p arguement decides which of the two stage needs to be + * performed; TRUE - SETUP and FALSE - IN+STATUS + * Returns 0 if success + */ +static int submit_single_step_set_feature( + struct usb_hcd *hcd, + struct urb *urb, + int is_setup +) { + struct ehci_hcd *ehci = hcd_to_ehci(hcd); + struct list_head qtd_list; + struct list_head *head; + + struct ehci_qtd *qtd, *qtd_prev; + dma_addr_t buf; + int len, maxpacket; + u32 token; + + INIT_LIST_HEAD(&qtd_list); + head = &qtd_list; + + /* URBs map to sequences of QTDs: one logical transaction */ + qtd = ehci_qtd_alloc(ehci, GFP_KERNEL); + if (unlikely(!qtd)) + return -1; + list_add_tail(&qtd->qtd_list, head); + qtd->urb = urb; + + token = QTD_STS_ACTIVE; + token |= (EHCI_TUNE_CERR << 10); + + len = urb->transfer_buffer_length; + /* + * Check if the request is to perform just the SETUP stage (getDesc) + * as in SINGLE_STEP_SET_FEATURE test, DATA stage (IN) happens + * 15 secs after the setup + */ + if (is_setup) { + /* SETUP pid */ + qtd_fill(ehci, qtd, urb->setup_dma, + sizeof(struct usb_ctrlrequest), + token | (2 /* "setup" */ << 8), 8); + + submit_async(ehci, urb, &qtd_list, GFP_ATOMIC); + return 0; /*Return now; we shall come back after 15 seconds*/ + } + + /* + * IN: data transfer stage: buffer setup : start the IN txn phase for + * the get_Desc SETUP which was sent 15seconds back + */ + token ^= QTD_TOGGLE; /*We need to start IN with DATA-1 Pid-sequence*/ + buf = urb->transfer_dma; + + token |= (1 /* "in" */ << 8); /*This is IN stage*/ + + maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, 0)); + + qtd_fill(ehci, qtd, buf, len, token, maxpacket); + + /* + * Our IN phase shall always be a short read; so keep the queue running + * and let it advance to the next qtd which zero length OUT status + */ + qtd->hw_alt_next = EHCI_LIST_END(ehci); + + /* STATUS stage for GetDesc control request */ + token ^= 0x0100; /* "in" <--> "out" */ + token |= QTD_TOGGLE; /* force DATA1 */ + + qtd_prev = qtd; + qtd = ehci_qtd_alloc(ehci, GFP_ATOMIC); + if (unlikely(!qtd)) + goto cleanup; + qtd->urb = urb; + qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma); + list_add_tail(&qtd->qtd_list, head); + + /* dont fill any data in such packets */ + qtd_fill(ehci, qtd, 0, 0, token, 0); + + /* by default, enable interrupt on urb completion */ + if (likely(!(urb->transfer_flags & URB_NO_INTERRUPT))) + qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC); + + submit_async(ehci, urb, &qtd_list, GFP_KERNEL); + + return 0; + +cleanup: + qtd_list_free(ehci, urb, head); + return -1; +} +#endif /* CONFIG_USB_HCD_TEST_MODE */ + +/*-------------------------------------------------------------------------*/ + +static void single_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh) +{ + struct ehci_qh *prev; + + /* Add to the end of the list of QHs waiting for the next IAAD */ + qh->qh_state = QH_STATE_UNLINK_WAIT; + list_add_tail(&qh->unlink_node, &ehci->async_unlink); + + /* Unlink it from the schedule */ + prev = ehci->async; + while (prev->qh_next.qh != qh) + prev = prev->qh_next.qh; + + prev->hw->hw_next = qh->hw->hw_next; + prev->qh_next = qh->qh_next; + if (ehci->qh_scan_next == qh) + ehci->qh_scan_next = qh->qh_next.qh; +} + +static void start_iaa_cycle(struct ehci_hcd *ehci) +{ + /* Do nothing if an IAA cycle is already running */ + if (ehci->iaa_in_progress) + return; + ehci->iaa_in_progress = true; + + /* If the controller isn't running, we don't have to wait for it */ + if (unlikely(ehci->rh_state < EHCI_RH_RUNNING)) { + end_unlink_async(ehci); + + /* Otherwise start a new IAA cycle */ + } else if (likely(ehci->rh_state == EHCI_RH_RUNNING)) { + + /* Make sure the unlinks are all visible to the hardware */ + wmb(); + + ehci_writel(ehci, ehci->command | CMD_IAAD, + &ehci->regs->command); + ehci_readl(ehci, &ehci->regs->command); + ehci_enable_event(ehci, EHCI_HRTIMER_IAA_WATCHDOG, true); + } +} + +/* the async qh for the qtds being unlinked are now gone from the HC */ + +static void end_unlink_async(struct ehci_hcd *ehci) +{ + struct ehci_qh *qh; + bool early_exit; + + if (ehci->has_synopsys_hc_bug) + ehci_writel(ehci, (u32) ehci->async->qh_dma, + &ehci->regs->async_next); + + /* The current IAA cycle has ended */ + ehci->iaa_in_progress = false; + + if (list_empty(&ehci->async_unlink)) + return; + qh = list_first_entry(&ehci->async_unlink, struct ehci_qh, + unlink_node); /* QH whose IAA cycle just ended */ + + /* + * If async_unlinking is set then this routine is already running, + * either on the stack or on another CPU. + */ + early_exit = ehci->async_unlinking; + + /* If the controller isn't running, process all the waiting QHs */ + if (ehci->rh_state < EHCI_RH_RUNNING) + list_splice_tail_init(&ehci->async_unlink, &ehci->async_idle); + + /* + * Intel (?) bug: The HC can write back the overlay region even + * after the IAA interrupt occurs. In self-defense, always go + * through two IAA cycles for each QH. + */ + else if (qh->qh_state == QH_STATE_UNLINK_WAIT) { + qh->qh_state = QH_STATE_UNLINK; + early_exit = true; + } + + /* Otherwise process only the first waiting QH (NVIDIA bug?) */ + else + list_move_tail(&qh->unlink_node, &ehci->async_idle); + + /* Start a new IAA cycle if any QHs are waiting for it */ + if (!list_empty(&ehci->async_unlink)) + start_iaa_cycle(ehci); + + /* + * Don't allow nesting or concurrent calls, + * or wait for the second IAA cycle for the next QH. + */ + if (early_exit) + return; + + /* Process the idle QHs */ + ehci->async_unlinking = true; + while (!list_empty(&ehci->async_idle)) { + qh = list_first_entry(&ehci->async_idle, struct ehci_qh, + unlink_node); + list_del(&qh->unlink_node); + + qh->qh_state = QH_STATE_IDLE; + qh->qh_next.qh = NULL; + + if (!list_empty(&qh->qtd_list)) + qh_completions(ehci, qh); + if (!list_empty(&qh->qtd_list) && + ehci->rh_state == EHCI_RH_RUNNING) + qh_link_async(ehci, qh); + disable_async(ehci); + } + ehci->async_unlinking = false; +} + +static void start_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh); + +static void unlink_empty_async(struct ehci_hcd *ehci) +{ + struct ehci_qh *qh; + struct ehci_qh *qh_to_unlink = NULL; + int count = 0; + + /* Find the last async QH which has been empty for a timer cycle */ + for (qh = ehci->async->qh_next.qh; qh; qh = qh->qh_next.qh) { + if (list_empty(&qh->qtd_list) && + qh->qh_state == QH_STATE_LINKED) { + ++count; + if (qh->unlink_cycle != ehci->async_unlink_cycle) + qh_to_unlink = qh; + } + } + + /* If nothing else is being unlinked, unlink the last empty QH */ + if (list_empty(&ehci->async_unlink) && qh_to_unlink) { + start_unlink_async(ehci, qh_to_unlink); + --count; + } + + /* Other QHs will be handled later */ + if (count > 0) { + ehci_enable_event(ehci, EHCI_HRTIMER_ASYNC_UNLINKS, true); + ++ehci->async_unlink_cycle; + } +} + +/* The root hub is suspended; unlink all the async QHs */ +static void __maybe_unused unlink_empty_async_suspended(struct ehci_hcd *ehci) +{ + struct ehci_qh *qh; + + while (ehci->async->qh_next.qh) { + qh = ehci->async->qh_next.qh; + WARN_ON(!list_empty(&qh->qtd_list)); + single_unlink_async(ehci, qh); + } + start_iaa_cycle(ehci); +} + +/* makes sure the async qh will become idle */ +/* caller must own ehci->lock */ + +static void start_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh) +{ + /* If the QH isn't linked then there's nothing we can do. */ + if (qh->qh_state != QH_STATE_LINKED) + return; + + single_unlink_async(ehci, qh); + start_iaa_cycle(ehci); +} + +/*-------------------------------------------------------------------------*/ + +static void scan_async (struct ehci_hcd *ehci) +{ + struct ehci_qh *qh; + bool check_unlinks_later = false; + + ehci->qh_scan_next = ehci->async->qh_next.qh; + while (ehci->qh_scan_next) { + qh = ehci->qh_scan_next; + ehci->qh_scan_next = qh->qh_next.qh; + + /* clean any finished work for this qh */ + if (!list_empty(&qh->qtd_list)) { + int temp; + + /* + * Unlinks could happen here; completion reporting + * drops the lock. That's why ehci->qh_scan_next + * always holds the next qh to scan; if the next qh + * gets unlinked then ehci->qh_scan_next is adjusted + * in single_unlink_async(). + */ + temp = qh_completions(ehci, qh); + if (unlikely(temp)) { + start_unlink_async(ehci, qh); + } else if (list_empty(&qh->qtd_list) + && qh->qh_state == QH_STATE_LINKED) { + qh->unlink_cycle = ehci->async_unlink_cycle; + check_unlinks_later = true; + } + } + } + + /* + * Unlink empty entries, reducing DMA usage as well + * as HCD schedule-scanning costs. Delay for any qh + * we just scanned, there's a not-unusual case that it + * doesn't stay idle for long. + */ + if (check_unlinks_later && ehci->rh_state == EHCI_RH_RUNNING && + !(ehci->enabled_hrtimer_events & + BIT(EHCI_HRTIMER_ASYNC_UNLINKS))) { + ehci_enable_event(ehci, EHCI_HRTIMER_ASYNC_UNLINKS, true); + ++ehci->async_unlink_cycle; + } +} |