Initial import

1 files changed, 1645 insertions, 0 deletions

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
new file mode 100644
index 000000000..b4ef410e5
--- /dev/null
+++ b/sound/usb/pcm.c
@@ -0,0 +1,1645 @@
+/*
+ *   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/bitrev.h>
+#include <linux/ratelimit.h>
+#include <linux/usb.h>
+#include <linux/usb/audio.h>
+#include <linux/usb/audio-v2.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+#include "usbaudio.h"
+#include "card.h"
+#include "quirks.h"
+#include "debug.h"
+#include "endpoint.h"
+#include "helper.h"
+#include "pcm.h"
+#include "clock.h"
+#include "power.h"
+
+#define SUBSTREAM_FLAG_DATA_EP_STARTED	0
+#define SUBSTREAM_FLAG_SYNC_EP_STARTED	1
+
+/* return the estimated delay based on USB frame counters */
+snd_pcm_uframes_t snd_usb_pcm_delay(struct snd_usb_substream *subs,
+				    unsigned int rate)
+{
+	int current_frame_number;
+	int frame_diff;
+	int est_delay;
+
+	if (!subs->last_delay)
+		return 0; /* short path */
+
+	current_frame_number = usb_get_current_frame_number(subs->dev);
+	/*
+	 * HCD implementations use different widths, use lower 8 bits.
+	 * The delay will be managed up to 256ms, which is more than
+	 * enough
+	 */
+	frame_diff = (current_frame_number - subs->last_frame_number) & 0xff;
+
+	/* Approximation based on number of samples per USB frame (ms),
+	   some truncation for 44.1 but the estimate is good enough */
+	est_delay =  frame_diff * rate / 1000;
+	if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK)
+		est_delay = subs->last_delay - est_delay;
+	else
+		est_delay = subs->last_delay + est_delay;
+
+	if (est_delay < 0)
+		est_delay = 0;
+	return est_delay;
+}
+
+/*
+ * return the current pcm pointer.  just based on the hwptr_done value.
+ */
+static snd_pcm_uframes_t snd_usb_pcm_pointer(struct snd_pcm_substream *substream)
+{
+	struct snd_usb_substream *subs;
+	unsigned int hwptr_done;
+
+	subs = (struct snd_usb_substream *)substream->runtime->private_data;
+	if (subs->stream->chip->shutdown)
+		return SNDRV_PCM_POS_XRUN;
+	spin_lock(&subs->lock);
+	hwptr_done = subs->hwptr_done;
+	substream->runtime->delay = snd_usb_pcm_delay(subs,
+						substream->runtime->rate);
+	spin_unlock(&subs->lock);
+	return hwptr_done / (substream->runtime->frame_bits >> 3);
+}
+
+/*
+ * find a matching audio format
+ */
+static struct audioformat *find_format(struct snd_usb_substream *subs)
+{
+	struct audioformat *fp;
+	struct audioformat *found = NULL;
+	int cur_attr = 0, attr;
+
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		if (!(fp->formats & pcm_format_to_bits(subs->pcm_format)))
+			continue;
+		if (fp->channels != subs->channels)
+			continue;
+		if (subs->cur_rate < fp->rate_min ||
+		    subs->cur_rate > fp->rate_max)
+			continue;
+		if (! (fp->rates & SNDRV_PCM_RATE_CONTINUOUS)) {
+			unsigned int i;
+			for (i = 0; i < fp->nr_rates; i++)
+				if (fp->rate_table[i] == subs->cur_rate)
+					break;
+			if (i >= fp->nr_rates)
+				continue;
+		}
+		attr = fp->ep_attr & USB_ENDPOINT_SYNCTYPE;
+		if (! found) {
+			found = fp;
+			cur_attr = attr;
+			continue;
+		}
+		/* avoid async out and adaptive in if the other method
+		 * supports the same format.
+		 * this is a workaround for the case like
+		 * M-audio audiophile USB.
+		 */
+		if (attr != cur_attr) {
+			if ((attr == USB_ENDPOINT_SYNC_ASYNC &&
+			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
+			    (attr == USB_ENDPOINT_SYNC_ADAPTIVE &&
+			     subs->direction == SNDRV_PCM_STREAM_CAPTURE))
+				continue;
+			if ((cur_attr == USB_ENDPOINT_SYNC_ASYNC &&
+			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
+			    (cur_attr == USB_ENDPOINT_SYNC_ADAPTIVE &&
+			     subs->direction == SNDRV_PCM_STREAM_CAPTURE)) {
+				found = fp;
+				cur_attr = attr;
+				continue;
+			}
+		}
+		/* find the format with the largest max. packet size */
+		if (fp->maxpacksize > found->maxpacksize) {
+			found = fp;
+			cur_attr = attr;
+		}
+	}
+	return found;
+}
+
+static int init_pitch_v1(struct snd_usb_audio *chip, int iface,
+			 struct usb_host_interface *alts,
+			 struct audioformat *fmt)
+{
+	struct usb_device *dev = chip->dev;
+	unsigned int ep;
+	unsigned char data[1];
+	int err;
+
+	ep = get_endpoint(alts, 0)->bEndpointAddress;
+
+	data[0] = 1;
+	if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
+				   USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_OUT,
+				   UAC_EP_CS_ATTR_PITCH_CONTROL << 8, ep,
+				   data, sizeof(data))) < 0) {
+		usb_audio_err(chip, "%d:%d: cannot set enable PITCH\n",
+			      iface, ep);
+		return err;
+	}
+
+	return 0;
+}
+
+static int init_pitch_v2(struct snd_usb_audio *chip, int iface,
+			 struct usb_host_interface *alts,
+			 struct audioformat *fmt)
+{
+	struct usb_device *dev = chip->dev;
+	unsigned char data[1];
+	int err;
+
+	data[0] = 1;
+	if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC2_CS_CUR,
+				   USB_TYPE_CLASS | USB_RECIP_ENDPOINT | USB_DIR_OUT,
+				   UAC2_EP_CS_PITCH << 8, 0,
+				   data, sizeof(data))) < 0) {
+		usb_audio_err(chip, "%d:%d: cannot set enable PITCH (v2)\n",
+			      iface, fmt->altsetting);
+		return err;
+	}
+
+	return 0;
+}
+
+/*
+ * initialize the pitch control and sample rate
+ */
+int snd_usb_init_pitch(struct snd_usb_audio *chip, int iface,
+		       struct usb_host_interface *alts,
+		       struct audioformat *fmt)
+{
+	/* if endpoint doesn't have pitch control, bail out */
+	if (!(fmt->attributes & UAC_EP_CS_ATTR_PITCH_CONTROL))
+		return 0;
+
+	switch (fmt->protocol) {
+	case UAC_VERSION_1:
+	default:
+		return init_pitch_v1(chip, iface, alts, fmt);
+
+	case UAC_VERSION_2:
+		return init_pitch_v2(chip, iface, alts, fmt);
+	}
+}
+
+static int start_endpoints(struct snd_usb_substream *subs, bool can_sleep)
+{
+	int err;
+
+	if (!subs->data_endpoint)
+		return -EINVAL;
+
+	if (!test_and_set_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags)) {
+		struct snd_usb_endpoint *ep = subs->data_endpoint;
+
+		dev_dbg(&subs->dev->dev, "Starting data EP @%p\n", ep);
+
+		ep->data_subs = subs;
+		err = snd_usb_endpoint_start(ep, can_sleep);
+		if (err < 0) {
+			clear_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags);
+			return err;
+		}
+	}
+
+	if (subs->sync_endpoint &&
+	    !test_and_set_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags)) {
+		struct snd_usb_endpoint *ep = subs->sync_endpoint;
+
+		if (subs->data_endpoint->iface != subs->sync_endpoint->iface ||
+		    subs->data_endpoint->altsetting != subs->sync_endpoint->altsetting) {
+			err = usb_set_interface(subs->dev,
+						subs->sync_endpoint->iface,
+						subs->sync_endpoint->altsetting);
+			if (err < 0) {
+				clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags);
+				dev_err(&subs->dev->dev,
+					   "%d:%d: cannot set interface (%d)\n",
+					   subs->sync_endpoint->iface,
+					   subs->sync_endpoint->altsetting, err);
+				return -EIO;
+			}
+		}
+
+		dev_dbg(&subs->dev->dev, "Starting sync EP @%p\n", ep);
+
+		ep->sync_slave = subs->data_endpoint;
+		err = snd_usb_endpoint_start(ep, can_sleep);
+		if (err < 0) {
+			clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static void stop_endpoints(struct snd_usb_substream *subs, bool wait)
+{
+	if (test_and_clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags))
+		snd_usb_endpoint_stop(subs->sync_endpoint);
+
+	if (test_and_clear_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags))
+		snd_usb_endpoint_stop(subs->data_endpoint);
+
+	if (wait) {
+		snd_usb_endpoint_sync_pending_stop(subs->sync_endpoint);
+		snd_usb_endpoint_sync_pending_stop(subs->data_endpoint);
+	}
+}
+
+static int search_roland_implicit_fb(struct usb_device *dev, int ifnum,
+				     unsigned int altsetting,
+				     struct usb_host_interface **alts,
+				     unsigned int *ep)
+{
+	struct usb_interface *iface;
+	struct usb_interface_descriptor *altsd;
+	struct usb_endpoint_descriptor *epd;
+
+	iface = usb_ifnum_to_if(dev, ifnum);
+	if (!iface || iface->num_altsetting < altsetting + 1)
+		return -ENOENT;
+	*alts = &iface->altsetting[altsetting];
+	altsd = get_iface_desc(*alts);
+	if (altsd->bAlternateSetting != altsetting ||
+	    altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC ||
+	    (altsd->bInterfaceSubClass != 2 &&
+	     altsd->bInterfaceProtocol != 2   ) ||
+	    altsd->bNumEndpoints < 1)
+		return -ENOENT;
+	epd = get_endpoint(*alts, 0);
+	if (!usb_endpoint_is_isoc_in(epd) ||
+	    (epd->bmAttributes & USB_ENDPOINT_USAGE_MASK) !=
+					USB_ENDPOINT_USAGE_IMPLICIT_FB)
+		return -ENOENT;
+	*ep = epd->bEndpointAddress;
+	return 0;
+}
+
+static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
+					 struct usb_device *dev,
+					 struct usb_interface_descriptor *altsd,
+					 unsigned int attr)
+{
+	struct usb_host_interface *alts;
+	struct usb_interface *iface;
+	unsigned int ep;
+
+	/* Implicit feedback sync EPs consumers are always playback EPs */
+	if (subs->direction != SNDRV_PCM_STREAM_PLAYBACK)
+		return 0;
+
+	switch (subs->stream->chip->usb_id) {
+	case USB_ID(0x0763, 0x2030): /* M-Audio Fast Track C400 */
+	case USB_ID(0x0763, 0x2031): /* M-Audio Fast Track C600 */
+		ep = 0x81;
+		iface = usb_ifnum_to_if(dev, 3);
+
+		if (!iface || iface->num_altsetting == 0)
+			return -EINVAL;
+
+		alts = &iface->altsetting[1];
+		goto add_sync_ep;
+		break;
+	case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
+	case USB_ID(0x0763, 0x2081):
+		ep = 0x81;
+		iface = usb_ifnum_to_if(dev, 2);
+
+		if (!iface || iface->num_altsetting == 0)
+			return -EINVAL;
+
+		alts = &iface->altsetting[1];
+		goto add_sync_ep;
+	}
+	if (attr == USB_ENDPOINT_SYNC_ASYNC &&
+	    altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
+	    altsd->bInterfaceProtocol == 2 &&
+	    altsd->bNumEndpoints == 1 &&
+	    USB_ID_VENDOR(subs->stream->chip->usb_id) == 0x0582 /* Roland */ &&
+	    search_roland_implicit_fb(dev, altsd->bInterfaceNumber + 1,
+				      altsd->bAlternateSetting,
+				      &alts, &ep) >= 0) {
+		goto add_sync_ep;
+	}
+
+	/* No quirk */
+	return 0;
+
+add_sync_ep:
+	subs->sync_endpoint = snd_usb_add_endpoint(subs->stream->chip,
+						   alts, ep, !subs->direction,
+						   SND_USB_ENDPOINT_TYPE_DATA);
+	if (!subs->sync_endpoint)
+		return -EINVAL;
+
+	subs->data_endpoint->sync_master = subs->sync_endpoint;
+
+	return 0;
+}
+
+static int set_sync_endpoint(struct snd_usb_substream *subs,
+			     struct audioformat *fmt,
+			     struct usb_device *dev,
+			     struct usb_host_interface *alts,
+			     struct usb_interface_descriptor *altsd)
+{
+	int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
+	unsigned int ep, attr;
+	bool implicit_fb;
+	int err;
+
+	/* we need a sync pipe in async OUT or adaptive IN mode */
+	/* check the number of EP, since some devices have broken
+	 * descriptors which fool us.  if it has only one EP,
+	 * assume it as adaptive-out or sync-in.
+	 */
+	attr = fmt->ep_attr & USB_ENDPOINT_SYNCTYPE;
+
+	err = set_sync_ep_implicit_fb_quirk(subs, dev, altsd, attr);
+	if (err < 0)
+		return err;
+
+	if (altsd->bNumEndpoints < 2)
+		return 0;
+
+	if ((is_playback && attr != USB_ENDPOINT_SYNC_ASYNC) ||
+	    (!is_playback && attr != USB_ENDPOINT_SYNC_ADAPTIVE))
+		return 0;
+
+	/* check sync-pipe endpoint */
+	/* ... and check descriptor size before accessing bSynchAddress
+	   because there is a version of the SB Audigy 2 NX firmware lacking
+	   the audio fields in the endpoint descriptors */
+	if ((get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != USB_ENDPOINT_XFER_ISOC ||
+	    (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+	     get_endpoint(alts, 1)->bSynchAddress != 0)) {
+		dev_err(&dev->dev,
+			"%d:%d : invalid sync pipe. bmAttributes %02x, bLength %d, bSynchAddress %02x\n",
+			   fmt->iface, fmt->altsetting,
+			   get_endpoint(alts, 1)->bmAttributes,
+			   get_endpoint(alts, 1)->bLength,
+			   get_endpoint(alts, 1)->bSynchAddress);
+		return -EINVAL;
+	}
+	ep = get_endpoint(alts, 1)->bEndpointAddress;
+	if (get_endpoint(alts, 0)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+	    ((is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress | USB_DIR_IN)) ||
+	     (!is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress & ~USB_DIR_IN)))) {
+		dev_err(&dev->dev,
+			"%d:%d : invalid sync pipe. is_playback %d, ep %02x, bSynchAddress %02x\n",
+			   fmt->iface, fmt->altsetting,
+			   is_playback, ep, get_endpoint(alts, 0)->bSynchAddress);
+		return -EINVAL;
+	}
+
+	implicit_fb = (get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_USAGE_MASK)
+			== USB_ENDPOINT_USAGE_IMPLICIT_FB;
+
+	subs->sync_endpoint = snd_usb_add_endpoint(subs->stream->chip,
+						   alts, ep, !subs->direction,
+						   implicit_fb ?
+							SND_USB_ENDPOINT_TYPE_DATA :
+							SND_USB_ENDPOINT_TYPE_SYNC);
+	if (!subs->sync_endpoint)
+		return -EINVAL;
+
+	subs->data_endpoint->sync_master = subs->sync_endpoint;
+
+	return 0;
+}
+
+/*
+ * find a matching format and set up the interface
+ */
+static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
+{
+	struct usb_device *dev = subs->dev;
+	struct usb_host_interface *alts;
+	struct usb_interface_descriptor *altsd;
+	struct usb_interface *iface;
+	int err;
+
+	iface = usb_ifnum_to_if(dev, fmt->iface);
+	if (WARN_ON(!iface))
+		return -EINVAL;
+	alts = &iface->altsetting[fmt->altset_idx];
+	altsd = get_iface_desc(alts);
+	if (WARN_ON(altsd->bAlternateSetting != fmt->altsetting))
+		return -EINVAL;
+
+	if (fmt == subs->cur_audiofmt)
+		return 0;
+
+	/* close the old interface */
+	if (subs->interface >= 0 && subs->interface != fmt->iface) {
+		err = usb_set_interface(subs->dev, subs->interface, 0);
+		if (err < 0) {
+			dev_err(&dev->dev,
+				"%d:%d: return to setting 0 failed (%d)\n",
+				fmt->iface, fmt->altsetting, err);
+			return -EIO;
+		}
+		subs->interface = -1;
+		subs->altset_idx = 0;
+	}
+
+	/* set interface */
+	if (subs->interface != fmt->iface ||
+	    subs->altset_idx != fmt->altset_idx) {
+
+		err = snd_usb_select_mode_quirk(subs, fmt);
+		if (err < 0)
+			return -EIO;
+
+		err = usb_set_interface(dev, fmt->iface, fmt->altsetting);
+		if (err < 0) {
+			dev_err(&dev->dev,
+				"%d:%d: usb_set_interface failed (%d)\n",
+				fmt->iface, fmt->altsetting, err);
+			return -EIO;
+		}
+		dev_dbg(&dev->dev, "setting usb interface %d:%d\n",
+			fmt->iface, fmt->altsetting);
+		subs->interface = fmt->iface;
+		subs->altset_idx = fmt->altset_idx;
+
+		snd_usb_set_interface_quirk(dev);
+	}
+
+	subs->data_endpoint = snd_usb_add_endpoint(subs->stream->chip,
+						   alts, fmt->endpoint, subs->direction,
+						   SND_USB_ENDPOINT_TYPE_DATA);
+
+	if (!subs->data_endpoint)
+		return -EINVAL;
+
+	err = set_sync_endpoint(subs, fmt, dev, alts, altsd);
+	if (err < 0)
+		return err;
+
+	err = snd_usb_init_pitch(subs->stream->chip, fmt->iface, alts, fmt);
+	if (err < 0)
+		return err;
+
+	subs->cur_audiofmt = fmt;
+
+	snd_usb_set_format_quirk(subs, fmt);
+
+	return 0;
+}
+
+/*
+ * Return the score of matching two audioformats.
+ * Veto the audioformat if:
+ * - It has no channels for some reason.
+ * - Requested PCM format is not supported.
+ * - Requested sample rate is not supported.
+ */
+static int match_endpoint_audioformats(struct snd_usb_substream *subs,
+				       struct audioformat *fp,
+				       struct audioformat *match, int rate,
+				       snd_pcm_format_t pcm_format)
+{
+	int i;
+	int score = 0;
+
+	if (fp->channels < 1) {
+		dev_dbg(&subs->dev->dev,
+			"%s: (fmt @%p) no channels\n", __func__, fp);
+		return 0;
+	}
+
+	if (!(fp->formats & pcm_format_to_bits(pcm_format))) {
+		dev_dbg(&subs->dev->dev,
+			"%s: (fmt @%p) no match for format %d\n", __func__,
+			fp, pcm_format);
+		return 0;
+	}
+
+	for (i = 0; i < fp->nr_rates; i++) {
+		if (fp->rate_table[i] == rate) {
+			score++;
+			break;
+		}
+	}
+	if (!score) {
+		dev_dbg(&subs->dev->dev,
+			"%s: (fmt @%p) no match for rate %d\n", __func__,
+			fp, rate);
+		return 0;
+	}
+
+	if (fp->channels == match->channels)
+		score++;
+
+	dev_dbg(&subs->dev->dev,
+		"%s: (fmt @%p) score %d\n", __func__, fp, score);
+
+	return score;
+}
+
+/*
+ * Configure the sync ep using the rate and pcm format of the data ep.
+ */
+static int configure_sync_endpoint(struct snd_usb_substream *subs)
+{
+	int ret;
+	struct audioformat *fp;
+	struct audioformat *sync_fp = NULL;
+	int cur_score = 0;
+	int sync_period_bytes = subs->period_bytes;
+	struct snd_usb_substream *sync_subs =
+		&subs->stream->substream[subs->direction ^ 1];
+
+	if (subs->sync_endpoint->type != SND_USB_ENDPOINT_TYPE_DATA ||
+	    !subs->stream)
+		return snd_usb_endpoint_set_params(subs->sync_endpoint,
+						   subs->pcm_format,
+						   subs->channels,
+						   subs->period_bytes,
+						   0, 0,
+						   subs->cur_rate,
+						   subs->cur_audiofmt,
+						   NULL);
+
+	/* Try to find the best matching audioformat. */
+	list_for_each_entry(fp, &sync_subs->fmt_list, list) {
+		int score = match_endpoint_audioformats(subs,
+							fp, subs->cur_audiofmt,
+			subs->cur_rate, subs->pcm_format);
+
+		if (score > cur_score) {
+			sync_fp = fp;
+			cur_score = score;
+		}
+	}
+
+	if (unlikely(sync_fp == NULL)) {
+		dev_err(&subs->dev->dev,
+			"%s: no valid audioformat for sync ep %x found\n",
+			__func__, sync_subs->ep_num);
+		return -EINVAL;
+	}
+
+	/*
+	 * Recalculate the period bytes if channel number differ between
+	 * data and sync ep audioformat.
+	 */
+	if (sync_fp->channels != subs->channels) {
+		sync_period_bytes = (subs->period_bytes / subs->channels) *
+			sync_fp->channels;
+		dev_dbg(&subs->dev->dev,
+			"%s: adjusted sync ep period bytes (%d -> %d)\n",
+			__func__, subs->period_bytes, sync_period_bytes);
+	}
+
+	ret = snd_usb_endpoint_set_params(subs->sync_endpoint,
+					  subs->pcm_format,
+					  sync_fp->channels,
+					  sync_period_bytes,
+					  0, 0,
+					  subs->cur_rate,
+					  sync_fp,
+					  NULL);
+
+	return ret;
+}
+
+/*
+ * configure endpoint params
+ *
+ * called  during initial setup and upon resume
+ */
+static int configure_endpoint(struct snd_usb_substream *subs)
+{
+	int ret;
+
+	/* format changed */
+	stop_endpoints(subs, true);
+	ret = snd_usb_endpoint_set_params(subs->data_endpoint,
+					  subs->pcm_format,
+					  subs->channels,
+					  subs->period_bytes,
+					  subs->period_frames,
+					  subs->buffer_periods,
+					  subs->cur_rate,
+					  subs->cur_audiofmt,
+					  subs->sync_endpoint);
+	if (ret < 0)
+		return ret;
+
+	if (subs->sync_endpoint)
+		ret = configure_sync_endpoint(subs);
+
+	return ret;
+}
+
+/*
+ * hw_params callback
+ *
+ * allocate a buffer and set the given audio format.
+ *
+ * so far we use a physically linear buffer although packetize transfer
+ * doesn't need a continuous area.
+ * if sg buffer is supported on the later version of alsa, we'll follow
+ * that.
+ */
+static int snd_usb_hw_params(struct snd_pcm_substream *substream,
+			     struct snd_pcm_hw_params *hw_params)
+{
+	struct snd_usb_substream *subs = substream->runtime->private_data;
+	struct audioformat *fmt;
+	int ret;
+
+	ret = snd_pcm_lib_alloc_vmalloc_buffer(substream,
+					       params_buffer_bytes(hw_params));
+	if (ret < 0)
+		return ret;
+
+	subs->pcm_format = params_format(hw_params);
+	subs->period_bytes = params_period_bytes(hw_params);
+	subs->period_frames = params_period_size(hw_params);
+	subs->buffer_periods = params_periods(hw_params);
+	subs->channels = params_channels(hw_params);
+	subs->cur_rate = params_rate(hw_params);
+
+	fmt = find_format(subs);
+	if (!fmt) {
+		dev_dbg(&subs->dev->dev,
+			"cannot set format: format = %#x, rate = %d, channels = %d\n",
+			   subs->pcm_format, subs->cur_rate, subs->channels);
+		return -EINVAL;
+	}
+
+	down_read(&subs->stream->chip->shutdown_rwsem);
+	if (subs->stream->chip->shutdown)
+		ret = -ENODEV;
+	else
+		ret = set_format(subs, fmt);
+	up_read(&subs->stream->chip->shutdown_rwsem);
+	if (ret < 0)
+		return ret;
+
+	subs->interface = fmt->iface;
+	subs->altset_idx = fmt->altset_idx;
+	subs->need_setup_ep = true;
+
+	return 0;
+}
+
+/*
+ * hw_free callback
+ *
+ * reset the audio format and release the buffer
+ */
+static int snd_usb_hw_free(struct snd_pcm_substream *substream)
+{
+	struct snd_usb_substream *subs = substream->runtime->private_data;
+
+	subs->cur_audiofmt = NULL;
+	subs->cur_rate = 0;
+	subs->period_bytes = 0;
+	down_read(&subs->stream->chip->shutdown_rwsem);
+	if (!subs->stream->chip->shutdown) {
+		stop_endpoints(subs, true);
+		snd_usb_endpoint_deactivate(subs->sync_endpoint);
+		snd_usb_endpoint_deactivate(subs->data_endpoint);
+	}
+	up_read(&subs->stream->chip->shutdown_rwsem);
+	return snd_pcm_lib_free_vmalloc_buffer(substream);
+}
+
+/*
+ * prepare callback
+ *
+ * only a few subtle things...
+ */
+static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct snd_usb_substream *subs = runtime->private_data;
+	struct usb_host_interface *alts;
+	struct usb_interface *iface;
+	int ret;
+
+	if (! subs->cur_audiofmt) {
+		dev_err(&subs->dev->dev, "no format is specified!\n");
+		return -ENXIO;
+	}
+
+	down_read(&subs->stream->chip->shutdown_rwsem);
+	if (subs->stream->chip->shutdown) {
+		ret = -ENODEV;
+		goto unlock;
+	}
+	if (snd_BUG_ON(!subs->data_endpoint)) {
+		ret = -EIO;
+		goto unlock;
+	}
+
+	snd_usb_endpoint_sync_pending_stop(subs->sync_endpoint);
+	snd_usb_endpoint_sync_pending_stop(subs->data_endpoint);
+
+	ret = set_format(subs, subs->cur_audiofmt);
+	if (ret < 0)
+		goto unlock;
+
+	iface = usb_ifnum_to_if(subs->dev, subs->cur_audiofmt->iface);
+	alts = &iface->altsetting[subs->cur_audiofmt->altset_idx];
+	ret = snd_usb_init_sample_rate(subs->stream->chip,
+				       subs->cur_audiofmt->iface,
+				       alts,
+				       subs->cur_audiofmt,
+				       subs->cur_rate);
+	if (ret < 0)
+		goto unlock;
+
+	if (subs->need_setup_ep) {
+		ret = configure_endpoint(subs);
+		if (ret < 0)
+			goto unlock;
+		subs->need_setup_ep = false;
+	}
+
+	/* some unit conversions in runtime */
+	subs->data_endpoint->maxframesize =
+		bytes_to_frames(runtime, subs->data_endpoint->maxpacksize);
+	subs->data_endpoint->curframesize =
+		bytes_to_frames(runtime, subs->data_endpoint->curpacksize);
+
+	/* reset the pointer */
+	subs->hwptr_done = 0;
+	subs->transfer_done = 0;
+	subs->last_delay = 0;
+	subs->last_frame_number = 0;
+	runtime->delay = 0;
+
+	/* for playback, submit the URBs now; otherwise, the first hwptr_done
+	 * updates for all URBs would happen at the same time when starting */
+	if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK)
+		ret = start_endpoints(subs, true);
+
+ unlock:
+	up_read(&subs->stream->chip->shutdown_rwsem);
+	return ret;
+}
+
+static struct snd_pcm_hardware snd_usb_hardware =
+{
+	.info =			SNDRV_PCM_INFO_MMAP |
+				SNDRV_PCM_INFO_MMAP_VALID |
+				SNDRV_PCM_INFO_BATCH |
+				SNDRV_PCM_INFO_INTERLEAVED |
+				SNDRV_PCM_INFO_BLOCK_TRANSFER |
+				SNDRV_PCM_INFO_PAUSE,
+	.buffer_bytes_max =	1024 * 1024,
+	.period_bytes_min =	64,
+	.period_bytes_max =	512 * 1024,
+	.periods_min =		2,
+	.periods_max =		1024,
+};
+
+static int hw_check_valid_format(struct snd_usb_substream *subs,
+				 struct snd_pcm_hw_params *params,
+				 struct audioformat *fp)
+{
+	struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
+	struct snd_interval *ct = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
+	struct snd_mask *fmts = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
+	struct snd_interval *pt = hw_param_interval(params, SNDRV_PCM_HW_PARAM_PERIOD_TIME);
+	struct snd_mask check_fmts;
+	unsigned int ptime;
+
+	/* check the format */
+	snd_mask_none(&check_fmts);
+	check_fmts.bits[0] = (u32)fp->formats;
+	check_fmts.bits[1] = (u32)(fp->formats >> 32);
+	snd_mask_intersect(&check_fmts, fmts);
+	if (snd_mask_empty(&check_fmts)) {
+		hwc_debug("   > check: no supported format %d\n", fp->format);
+		return 0;
+	}
+	/* check the channels */
+	if (fp->channels < ct->min || fp->channels > ct->max) {
+		hwc_debug("   > check: no valid channels %d (%d/%d)\n", fp->channels, ct->min, ct->max);
+		return 0;
+	}
+	/* check the rate is within the range */
+	if (fp->rate_min > it->max || (fp->rate_min == it->max && it->openmax)) {
+		hwc_debug("   > check: rate_min %d > max %d\n", fp->rate_min, it->max);
+		return 0;
+	}
+	if (fp->rate_max < it->min || (fp->rate_max == it->min && it->openmin)) {
+		hwc_debug("   > check: rate_max %d < min %d\n", fp->rate_max, it->min);
+		return 0;
+	}
+	/* check whether the period time is >= the data packet interval */
+	if (subs->speed != USB_SPEED_FULL) {
+		ptime = 125 * (1 << fp->datainterval);
+		if (ptime > pt->max || (ptime == pt->max && pt->openmax)) {
+			hwc_debug("   > check: ptime %u > max %u\n", ptime, pt->max);
+			return 0;
+		}
+	}
+	return 1;
+}
+
+static int hw_rule_rate(struct snd_pcm_hw_params *params,
+			struct snd_pcm_hw_rule *rule)
+{
+	struct snd_usb_substream *subs = rule->private;
+	struct audioformat *fp;
+	struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
+	unsigned int rmin, rmax;
+	int changed;
+
+	hwc_debug("hw_rule_rate: (%d,%d)\n", it->min, it->max);
+	changed = 0;
+	rmin = rmax = 0;
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		if (!hw_check_valid_format(subs, params, fp))
+			continue;
+		if (changed++) {
+			if (rmin > fp->rate_min)
+				rmin = fp->rate_min;
+			if (rmax < fp->rate_max)
+				rmax = fp->rate_max;
+		} else {
+			rmin = fp->rate_min;
+			rmax = fp->rate_max;
+		}
+	}
+
+	if (!changed) {
+		hwc_debug("  --> get empty\n");
+		it->empty = 1;
+		return -EINVAL;
+	}
+
+	changed = 0;
+	if (it->min < rmin) {
+		it->min = rmin;
+		it->openmin = 0;
+		changed = 1;
+	}
+	if (it->max > rmax) {
+		it->max = rmax;
+		it->openmax = 0;
+		changed = 1;
+	}
+	if (snd_interval_checkempty(it)) {
+		it->empty = 1;
+		return -EINVAL;
+	}
+	hwc_debug("  --> (%d, %d) (changed = %d)\n", it->min, it->max, changed);
+	return changed;
+}
+
+
+static int hw_rule_channels(struct snd_pcm_hw_params *params,
+			    struct snd_pcm_hw_rule *rule)
+{
+	struct snd_usb_substream *subs = rule->private;
+	struct audioformat *fp;
+	struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
+	unsigned int rmin, rmax;
+	int changed;
+
+	hwc_debug("hw_rule_channels: (%d,%d)\n", it->min, it->max);
+	changed = 0;
+	rmin = rmax = 0;
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		if (!hw_check_valid_format(subs, params, fp))
+			continue;
+		if (changed++) {
+			if (rmin > fp->channels)
+				rmin = fp->channels;
+			if (rmax < fp->channels)
+				rmax = fp->channels;
+		} else {
+			rmin = fp->channels;
+			rmax = fp->channels;
+		}
+	}
+
+	if (!changed) {
+		hwc_debug("  --> get empty\n");
+		it->empty = 1;
+		return -EINVAL;
+	}
+
+	changed = 0;
+	if (it->min < rmin) {
+		it->min = rmin;
+		it->openmin = 0;
+		changed = 1;
+	}
+	if (it->max > rmax) {
+		it->max = rmax;
+		it->openmax = 0;
+		changed = 1;
+	}
+	if (snd_interval_checkempty(it)) {
+		it->empty = 1;
+		return -EINVAL;
+	}
+	hwc_debug("  --> (%d, %d) (changed = %d)\n", it->min, it->max, changed);
+	return changed;
+}
+
+static int hw_rule_format(struct snd_pcm_hw_params *params,
+			  struct snd_pcm_hw_rule *rule)
+{
+	struct snd_usb_substream *subs = rule->private;
+	struct audioformat *fp;
+	struct snd_mask *fmt = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
+	u64 fbits;
+	u32 oldbits[2];
+	int changed;
+
+	hwc_debug("hw_rule_format: %x:%x\n", fmt->bits[0], fmt->bits[1]);
+	fbits = 0;
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		if (!hw_check_valid_format(subs, params, fp))
+			continue;
+		fbits |= fp->formats;
+	}
+
+	oldbits[0] = fmt->bits[0];
+	oldbits[1] = fmt->bits[1];
+	fmt->bits[0] &= (u32)fbits;
+	fmt->bits[1] &= (u32)(fbits >> 32);
+	if (!fmt->bits[0] && !fmt->bits[1]) {
+		hwc_debug("  --> get empty\n");
+		return -EINVAL;
+	}
+	changed = (oldbits[0] != fmt->bits[0] || oldbits[1] != fmt->bits[1]);
+	hwc_debug("  --> %x:%x (changed = %d)\n", fmt->bits[0], fmt->bits[1], changed);
+	return changed;
+}
+
+static int hw_rule_period_time(struct snd_pcm_hw_params *params,
+			       struct snd_pcm_hw_rule *rule)
+{
+	struct snd_usb_substream *subs = rule->private;
+	struct audioformat *fp;
+	struct snd_interval *it;
+	unsigned char min_datainterval;
+	unsigned int pmin;
+	int changed;
+
+	it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_PERIOD_TIME);
+	hwc_debug("hw_rule_period_time: (%u,%u)\n", it->min, it->max);
+	min_datainterval = 0xff;
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		if (!hw_check_valid_format(subs, params, fp))
+			continue;
+		min_datainterval = min(min_datainterval, fp->datainterval);
+	}
+	if (min_datainterval == 0xff) {
+		hwc_debug("  --> get empty\n");
+		it->empty = 1;
+		return -EINVAL;
+	}
+	pmin = 125 * (1 << min_datainterval);
+	changed = 0;
+	if (it->min < pmin) {
+		it->min = pmin;
+		it->openmin = 0;
+		changed = 1;
+	}
+	if (snd_interval_checkempty(it)) {
+		it->empty = 1;
+		return -EINVAL;
+	}
+	hwc_debug("  --> (%u,%u) (changed = %d)\n", it->min, it->max, changed);
+	return changed;
+}
+
+/*
+ *  If the device supports unusual bit rates, does the request meet these?
+ */
+static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
+				  struct snd_usb_substream *subs)
+{
+	struct audioformat *fp;
+	int *rate_list;
+	int count = 0, needs_knot = 0;
+	int err;
+
+	kfree(subs->rate_list.list);
+	subs->rate_list.list = NULL;
+
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		if (fp->rates & SNDRV_PCM_RATE_CONTINUOUS)
+			return 0;
+		count += fp->nr_rates;
+		if (fp->rates & SNDRV_PCM_RATE_KNOT)
+			needs_knot = 1;
+	}
+	if (!needs_knot)
+		return 0;
+
+	subs->rate_list.list = rate_list =
+		kmalloc(sizeof(int) * count, GFP_KERNEL);
+	if (!subs->rate_list.list)
+		return -ENOMEM;
+	subs->rate_list.count = count;
+	subs->rate_list.mask = 0;
+	count = 0;
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		int i;
+		for (i = 0; i < fp->nr_rates; i++)
+			rate_list[count++] = fp->rate_table[i];
+	}
+	err = snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
+					 &subs->rate_list);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+
+/*
+ * set up the runtime hardware information.
+ */
+
+static int setup_hw_info(struct snd_pcm_runtime *runtime, struct snd_usb_substream *subs)
+{
+	struct audioformat *fp;
+	unsigned int pt, ptmin;
+	int param_period_time_if_needed;
+	int err;
+
+	runtime->hw.formats = subs->formats;
+
+	runtime->hw.rate_min = 0x7fffffff;
+	runtime->hw.rate_max = 0;
+	runtime->hw.channels_min = 256;
+	runtime->hw.channels_max = 0;
+	runtime->hw.rates = 0;
+	ptmin = UINT_MAX;
+	/* check min/max rates and channels */
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		runtime->hw.rates |= fp->rates;
+		if (runtime->hw.rate_min > fp->rate_min)
+			runtime->hw.rate_min = fp->rate_min;
+		if (runtime->hw.rate_max < fp->rate_max)
+			runtime->hw.rate_max = fp->rate_max;
+		if (runtime->hw.channels_min > fp->channels)
+			runtime->hw.channels_min = fp->channels;
+		if (runtime->hw.channels_max < fp->channels)
+			runtime->hw.channels_max = fp->channels;
+		if (fp->fmt_type == UAC_FORMAT_TYPE_II && fp->frame_size > 0) {
+			/* FIXME: there might be more than one audio formats... */
+			runtime->hw.period_bytes_min = runtime->hw.period_bytes_max =
+				fp->frame_size;
+		}
+		pt = 125 * (1 << fp->datainterval);
+		ptmin = min(ptmin, pt);
+	}
+	err = snd_usb_autoresume(subs->stream->chip);
+	if (err < 0)
+		return err;
+
+	param_period_time_if_needed = SNDRV_PCM_HW_PARAM_PERIOD_TIME;
+	if (subs->speed == USB_SPEED_FULL)
+		/* full speed devices have fixed data packet interval */
+		ptmin = 1000;
+	if (ptmin == 1000)
+		/* if period time doesn't go below 1 ms, no rules needed */
+		param_period_time_if_needed = -1;
+	snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_TIME,
+				     ptmin, UINT_MAX);
+
+	if ((err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
+				       hw_rule_rate, subs,
+				       SNDRV_PCM_HW_PARAM_FORMAT,
+				       SNDRV_PCM_HW_PARAM_CHANNELS,
+				       param_period_time_if_needed,
+				       -1)) < 0)
+		goto rep_err;
+	if ((err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
+				       hw_rule_channels, subs,
+				       SNDRV_PCM_HW_PARAM_FORMAT,
+				       SNDRV_PCM_HW_PARAM_RATE,
+				       param_period_time_if_needed,
+				       -1)) < 0)
+		goto rep_err;
+	if ((err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_FORMAT,
+				       hw_rule_format, subs,
+				       SNDRV_PCM_HW_PARAM_RATE,
+				       SNDRV_PCM_HW_PARAM_CHANNELS,
+				       param_period_time_if_needed,
+				       -1)) < 0)
+		goto rep_err;
+	if (param_period_time_if_needed >= 0) {
+		err = snd_pcm_hw_rule_add(runtime, 0,
+					  SNDRV_PCM_HW_PARAM_PERIOD_TIME,
+					  hw_rule_period_time, subs,
+					  SNDRV_PCM_HW_PARAM_FORMAT,
+					  SNDRV_PCM_HW_PARAM_CHANNELS,
+					  SNDRV_PCM_HW_PARAM_RATE,
+					  -1);
+		if (err < 0)
+			goto rep_err;
+	}
+	if ((err = snd_usb_pcm_check_knot(runtime, subs)) < 0)
+		goto rep_err;
+	return 0;
+
+rep_err:
+	snd_usb_autosuspend(subs->stream->chip);
+	return err;
+}
+
+static int snd_usb_pcm_open(struct snd_pcm_substream *substream, int direction)
+{
+	struct snd_usb_stream *as = snd_pcm_substream_chip(substream);
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct snd_usb_substream *subs = &as->substream[direction];
+
+	subs->interface = -1;
+	subs->altset_idx = 0;
+	runtime->hw = snd_usb_hardware;
+	runtime->private_data = subs;
+	subs->pcm_substream = substream;
+	/* runtime PM is also done there */
+
+	/* initialize DSD/DOP context */
+	subs->dsd_dop.byte_idx = 0;
+	subs->dsd_dop.channel = 0;
+	subs->dsd_dop.marker = 1;
+
+	return setup_hw_info(runtime, subs);
+}
+
+static int snd_usb_pcm_close(struct snd_pcm_substream *substream, int direction)
+{
+	struct snd_usb_stream *as = snd_pcm_substream_chip(substream);
+	struct snd_usb_substream *subs = &as->substream[direction];
+
+	stop_endpoints(subs, true);
+
+	if (!as->chip->shutdown && subs->interface >= 0) {
+		usb_set_interface(subs->dev, subs->interface, 0);
+		subs->interface = -1;
+	}
+
+	subs->pcm_substream = NULL;
+	snd_usb_autosuspend(subs->stream->chip);
+
+	return 0;
+}
+
+/* Since a URB can handle only a single linear buffer, we must use double
+ * buffering when the data to be transferred overflows the buffer boundary.
+ * To avoid inconsistencies when updating hwptr_done, we use double buffering
+ * for all URBs.
+ */
+static void retire_capture_urb(struct snd_usb_substream *subs,
+			       struct urb *urb)
+{
+	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;
+	unsigned int stride, frames, bytes, oldptr;
+	int i, period_elapsed = 0;
+	unsigned long flags;
+	unsigned char *cp;
+	int current_frame_number;
+
+	/* read frame number here, update pointer in critical section */
+	current_frame_number = usb_get_current_frame_number(subs->dev);
+
+	stride = runtime->frame_bits >> 3;
+
+	for (i = 0; i < urb->number_of_packets; i++) {
+		cp = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset + subs->pkt_offset_adj;
+		if (urb->iso_frame_desc[i].status && printk_ratelimit()) {
+			dev_dbg(&subs->dev->dev, "frame %d active: %d\n",
+				i, urb->iso_frame_desc[i].status);
+			// continue;
+		}
+		bytes = urb->iso_frame_desc[i].actual_length;
+		frames = bytes / stride;
+		if (!subs->txfr_quirk)
+			bytes = frames * stride;
+		if (bytes % (runtime->sample_bits >> 3) != 0) {
+			int oldbytes = bytes;
+			bytes = frames * stride;
+			dev_warn(&subs->dev->dev,
+				 "Corrected urb data len. %d->%d\n",
+							oldbytes, bytes);
+		}
+		/* update the current pointer */
+		spin_lock_irqsave(&subs->lock, flags);
+		oldptr = subs->hwptr_done;
+		subs->hwptr_done += bytes;
+		if (subs->hwptr_done >= runtime->buffer_size * stride)
+			subs->hwptr_done -= runtime->buffer_size * stride;
+		frames = (bytes + (oldptr % stride)) / stride;
+		subs->transfer_done += frames;
+		if (subs->transfer_done >= runtime->period_size) {
+			subs->transfer_done -= runtime->period_size;
+			period_elapsed = 1;
+		}
+		/* capture delay is by construction limited to one URB,
+		 * reset delays here
+		 */
+		runtime->delay = subs->last_delay = 0;
+
+		/* realign last_frame_number */
+		subs->last_frame_number = current_frame_number;
+		subs->last_frame_number &= 0xFF; /* keep 8 LSBs */
+
+		spin_unlock_irqrestore(&subs->lock, flags);
+		/* copy a data chunk */
+		if (oldptr + bytes > runtime->buffer_size * stride) {
+			unsigned int bytes1 =
+					runtime->buffer_size * stride - oldptr;
+			memcpy(runtime->dma_area + oldptr, cp, bytes1);
+			memcpy(runtime->dma_area, cp + bytes1, bytes - bytes1);
+		} else {
+			memcpy(runtime->dma_area + oldptr, cp, bytes);
+		}
+	}
+
+	if (period_elapsed)
+		snd_pcm_period_elapsed(subs->pcm_substream);
+}
+
+static inline void fill_playback_urb_dsd_dop(struct snd_usb_substream *subs,
+					     struct urb *urb, unsigned int bytes)
+{
+	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;
+	unsigned int stride = runtime->frame_bits >> 3;
+	unsigned int dst_idx = 0;
+	unsigned int src_idx = subs->hwptr_done;
+	unsigned int wrap = runtime->buffer_size * stride;
+	u8 *dst = urb->transfer_buffer;
+	u8 *src = runtime->dma_area;
+	u8 marker[] = { 0x05, 0xfa };
+
+	/*
+	 * The DSP DOP format defines a way to transport DSD samples over
+	 * normal PCM data endpoints. It requires stuffing of marker bytes
+	 * (0x05 and 0xfa, alternating per sample frame), and then expects
+	 * 2 additional bytes of actual payload. The whole frame is stored
+	 * LSB.
+	 *
+	 * Hence, for a stereo transport, the buffer layout looks like this,
+	 * where L refers to left channel samples and R to right.
+	 *
+	 *   L1 L2 0x05   R1 R2 0x05   L3 L4 0xfa  R3 R4 0xfa
+	 *   L5 L6 0x05   R5 R6 0x05   L7 L8 0xfa  R7 R8 0xfa
+	 *   .....
+	 *
+	 */
+
+	while (bytes--) {
+		if (++subs->dsd_dop.byte_idx == 3) {
+			/* frame boundary? */
+			dst[dst_idx++] = marker[subs->dsd_dop.marker];
+			src_idx += 2;
+			subs->dsd_dop.byte_idx = 0;
+
+			if (++subs->dsd_dop.channel % runtime->channels == 0) {
+				/* alternate the marker */
+				subs->dsd_dop.marker++;
+				subs->dsd_dop.marker %= ARRAY_SIZE(marker);
+				subs->dsd_dop.channel = 0;
+			}
+		} else {
+			/* stuff the DSD payload */
+			int idx = (src_idx + subs->dsd_dop.byte_idx - 1) % wrap;
+
+			if (subs->cur_audiofmt->dsd_bitrev)
+				dst[dst_idx++] = bitrev8(src[idx]);
+			else
+				dst[dst_idx++] = src[idx];
+
+			subs->hwptr_done++;
+		}
+	}
+}
+
+static void prepare_playback_urb(struct snd_usb_substream *subs,
+				 struct urb *urb)
+{
+	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;
+	struct snd_usb_endpoint *ep = subs->data_endpoint;
+	struct snd_urb_ctx *ctx = urb->context;
+	unsigned int counts, frames, bytes;
+	int i, stride, period_elapsed = 0;
+	unsigned long flags;
+
+	stride = runtime->frame_bits >> 3;
+
+	frames = 0;
+	urb->number_of_packets = 0;
+	spin_lock_irqsave(&subs->lock, flags);
+	subs->frame_limit += ep->max_urb_frames;
+	for (i = 0; i < ctx->packets; i++) {
+		if (ctx->packet_size[i])
+			counts = ctx->packet_size[i];
+		else
+			counts = snd_usb_endpoint_next_packet_size(ep);
+
+		/* set up descriptor */
+		urb->iso_frame_desc[i].offset = frames * ep->stride;
+		urb->iso_frame_desc[i].length = counts * ep->stride;
+		frames += counts;
+		urb->number_of_packets++;
+		subs->transfer_done += counts;
+		if (subs->transfer_done >= runtime->period_size) {
+			subs->transfer_done -= runtime->period_size;
+			subs->frame_limit = 0;
+			period_elapsed = 1;
+			if (subs->fmt_type == UAC_FORMAT_TYPE_II) {
+				if (subs->transfer_done > 0) {
+					/* FIXME: fill-max mode is not
+					 * supported yet */
+					frames -= subs->transfer_done;
+					counts -= subs->transfer_done;
+					urb->iso_frame_desc[i].length =
+						counts * ep->stride;
+					subs->transfer_done = 0;
+				}
+				i++;
+				if (i < ctx->packets) {
+					/* add a transfer delimiter */
+					urb->iso_frame_desc[i].offset =
+						frames * ep->stride;
+					urb->iso_frame_desc[i].length = 0;
+					urb->number_of_packets++;
+				}
+				break;
+			}
+		}
+		/* finish at the period boundary or after enough frames */
+		if ((period_elapsed ||
+				subs->transfer_done >= subs->frame_limit) &&
+		    !snd_usb_endpoint_implicit_feedback_sink(ep))
+			break;
+	}
+	bytes = frames * ep->stride;
+
+	if (unlikely(subs->pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE &&
+		     subs->cur_audiofmt->dsd_dop)) {
+		fill_playback_urb_dsd_dop(subs, urb, bytes);
+	} else if (unlikely(subs->pcm_format == SNDRV_PCM_FORMAT_DSD_U8 &&
+			   subs->cur_audiofmt->dsd_bitrev)) {
+		/* bit-reverse the bytes */
+		u8 *buf = urb->transfer_buffer;
+		for (i = 0; i < bytes; i++) {
+			int idx = (subs->hwptr_done + i)
+				% (runtime->buffer_size * stride);
+			buf[i] = bitrev8(runtime->dma_area[idx]);
+		}
+
+		subs->hwptr_done += bytes;
+	} else {
+		/* usual PCM */
+		if (subs->hwptr_done + bytes > runtime->buffer_size * stride) {
+			/* err, the transferred area goes over buffer boundary. */
+			unsigned int bytes1 =
+				runtime->buffer_size * stride - subs->hwptr_done;
+			memcpy(urb->transfer_buffer,
+			       runtime->dma_area + subs->hwptr_done, bytes1);
+			memcpy(urb->transfer_buffer + bytes1,
+			       runtime->dma_area, bytes - bytes1);
+		} else {
+			memcpy(urb->transfer_buffer,
+			       runtime->dma_area + subs->hwptr_done, bytes);
+		}
+
+		subs->hwptr_done += bytes;
+	}
+
+	if (subs->hwptr_done >= runtime->buffer_size * stride)
+		subs->hwptr_done -= runtime->buffer_size * stride;
+
+	/* update delay with exact number of samples queued */
+	runtime->delay = subs->last_delay;
+	runtime->delay += frames;
+	subs->last_delay = runtime->delay;
+
+	/* realign last_frame_number */
+	subs->last_frame_number = usb_get_current_frame_number(subs->dev);
+	subs->last_frame_number &= 0xFF; /* keep 8 LSBs */
+
+	if (subs->trigger_tstamp_pending_update) {
+		/* this is the first actual URB submitted,
+		 * update trigger timestamp to reflect actual start time
+		 */
+		snd_pcm_gettime(runtime, &runtime->trigger_tstamp);
+		subs->trigger_tstamp_pending_update = false;
+	}
+
+	spin_unlock_irqrestore(&subs->lock, flags);
+	urb->transfer_buffer_length = bytes;
+	if (period_elapsed)
+		snd_pcm_period_elapsed(subs->pcm_substream);
+}
+
+/*
+ * process after playback data complete
+ * - decrease the delay count again
+ */
+static void retire_playback_urb(struct snd_usb_substream *subs,
+			       struct urb *urb)
+{
+	unsigned long flags;
+	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;
+	struct snd_usb_endpoint *ep = subs->data_endpoint;
+	int processed = urb->transfer_buffer_length / ep->stride;
+	int est_delay;
+
+	/* ignore the delay accounting when procssed=0 is given, i.e.
+	 * silent payloads are procssed before handling the actual data
+	 */
+	if (!processed)
+		return;
+
+	spin_lock_irqsave(&subs->lock, flags);
+	if (!subs->last_delay)
+		goto out; /* short path */
+
+	est_delay = snd_usb_pcm_delay(subs, runtime->rate);
+	/* update delay with exact number of samples played */
+	if (processed > subs->last_delay)
+		subs->last_delay = 0;
+	else
+		subs->last_delay -= processed;
+	runtime->delay = subs->last_delay;
+
+	/*
+	 * Report when delay estimate is off by more than 2ms.
+	 * The error should be lower than 2ms since the estimate relies
+	 * on two reads of a counter updated every ms.
+	 */
+	if (abs(est_delay - subs->last_delay) * 1000 > runtime->rate * 2)
+		dev_dbg_ratelimited(&subs->dev->dev,
+			"delay: estimated %d, actual %d\n",
+			est_delay, subs->last_delay);
+
+	if (!subs->running) {
+		/* update last_frame_number for delay counting here since
+		 * prepare_playback_urb won't be called during pause
+		 */
+		subs->last_frame_number =
+			usb_get_current_frame_number(subs->dev) & 0xff;
+	}
+
+ out:
+	spin_unlock_irqrestore(&subs->lock, flags);
+}
+
+static int snd_usb_playback_open(struct snd_pcm_substream *substream)
+{
+	return snd_usb_pcm_open(substream, SNDRV_PCM_STREAM_PLAYBACK);
+}
+
+static int snd_usb_playback_close(struct snd_pcm_substream *substream)
+{
+	return snd_usb_pcm_close(substream, SNDRV_PCM_STREAM_PLAYBACK);
+}
+
+static int snd_usb_capture_open(struct snd_pcm_substream *substream)
+{
+	return snd_usb_pcm_open(substream, SNDRV_PCM_STREAM_CAPTURE);
+}
+
+static int snd_usb_capture_close(struct snd_pcm_substream *substream)
+{
+	return snd_usb_pcm_close(substream, SNDRV_PCM_STREAM_CAPTURE);
+}
+
+static int snd_usb_substream_playback_trigger(struct snd_pcm_substream *substream,
+					      int cmd)
+{
+	struct snd_usb_substream *subs = substream->runtime->private_data;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+		subs->trigger_tstamp_pending_update = true;
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		subs->data_endpoint->prepare_data_urb = prepare_playback_urb;
+		subs->data_endpoint->retire_data_urb = retire_playback_urb;
+		subs->running = 1;
+		return 0;
+	case SNDRV_PCM_TRIGGER_STOP:
+		stop_endpoints(subs, false);
+		subs->running = 0;
+		return 0;
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		subs->data_endpoint->prepare_data_urb = NULL;
+		/* keep retire_data_urb for delay calculation */
+		subs->data_endpoint->retire_data_urb = retire_playback_urb;
+		subs->running = 0;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream,
+					     int cmd)
+{
+	int err;
+	struct snd_usb_substream *subs = substream->runtime->private_data;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+		err = start_endpoints(subs, false);
+		if (err < 0)
+			return err;
+
+		subs->data_endpoint->retire_data_urb = retire_capture_urb;
+		subs->running = 1;
+		return 0;
+	case SNDRV_PCM_TRIGGER_STOP:
+		stop_endpoints(subs, false);
+		subs->running = 0;
+		return 0;
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		subs->data_endpoint->retire_data_urb = NULL;
+		subs->running = 0;
+		return 0;
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		subs->data_endpoint->retire_data_urb = retire_capture_urb;
+		subs->running = 1;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static struct snd_pcm_ops snd_usb_playback_ops = {
+	.open =		snd_usb_playback_open,
+	.close =	snd_usb_playback_close,
+	.ioctl =	snd_pcm_lib_ioctl,
+	.hw_params =	snd_usb_hw_params,
+	.hw_free =	snd_usb_hw_free,
+	.prepare =	snd_usb_pcm_prepare,
+	.trigger =	snd_usb_substream_playback_trigger,
+	.pointer =	snd_usb_pcm_pointer,
+	.page =		snd_pcm_lib_get_vmalloc_page,
+	.mmap =		snd_pcm_lib_mmap_vmalloc,
+};
+
+static struct snd_pcm_ops snd_usb_capture_ops = {
+	.open =		snd_usb_capture_open,
+	.close =	snd_usb_capture_close,
+	.ioctl =	snd_pcm_lib_ioctl,
+	.hw_params =	snd_usb_hw_params,
+	.hw_free =	snd_usb_hw_free,
+	.prepare =	snd_usb_pcm_prepare,
+	.trigger =	snd_usb_substream_capture_trigger,
+	.pointer =	snd_usb_pcm_pointer,
+	.page =		snd_pcm_lib_get_vmalloc_page,
+	.mmap =		snd_pcm_lib_mmap_vmalloc,
+};
+
+void snd_usb_set_pcm_ops(struct snd_pcm *pcm, int stream)
+{
+	snd_pcm_set_ops(pcm, stream,
+			stream == SNDRV_PCM_STREAM_PLAYBACK ?
+			&snd_usb_playback_ops : &snd_usb_capture_ops);
+}