1 files changed, 919 insertions, 166 deletions

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index b8dcbf407bb..c62a1659106 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -16,6 +16,8 @@
 
 #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>
@@ -28,12 +30,47 @@
 #include "card.h"
 #include "quirks.h"
 #include "debug.h"
-#include "urb.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.
  */
@@ -43,8 +80,12 @@ static snd_pcm_uframes_t snd_usb_pcm_pointer(struct snd_pcm_substream *substream
 	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);
 }
@@ -52,26 +93,24 @@ static snd_pcm_uframes_t snd_usb_pcm_pointer(struct snd_pcm_substream *substream
 /*
  * find a matching audio format
  */
-static struct audioformat *find_format(struct snd_usb_substream *subs, unsigned int format,
-				       unsigned int rate, unsigned int channels)
+static struct audioformat *find_format(struct snd_usb_substream *subs)
 {
-	struct list_head *p;
+	struct audioformat *fp;
 	struct audioformat *found = NULL;
 	int cur_attr = 0, attr;
 
-	list_for_each(p, &subs->fmt_list) {
-		struct audioformat *fp;
-		fp = list_entry(p, struct audioformat, list);
-		if (!(fp->formats & (1uLL << format)))
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		if (!(fp->formats & pcm_format_to_bits(subs->pcm_format)))
 			continue;
-		if (fp->channels != channels)
+		if (fp->channels != subs->channels)
 			continue;
-		if (rate < fp->rate_min || rate > fp->rate_max)
+		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] == rate)
+				if (fp->rate_table[i] == subs->cur_rate)
 					break;
 			if (i >= fp->nr_rates)
 				continue;
@@ -126,9 +165,9 @@ static int init_pitch_v1(struct snd_usb_audio *chip, int iface,
 	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), 1000)) < 0) {
-		snd_printk(KERN_ERR "%d:%d:%d: cannot set enable PITCH\n",
-			   dev->devnum, iface, ep);
+				   data, sizeof(data))) < 0) {
+		usb_audio_err(chip, "%d:%d: cannot set enable PITCH\n",
+			      iface, ep);
 		return err;
 	}
 
@@ -141,18 +180,15 @@ static int init_pitch_v2(struct snd_usb_audio *chip, int iface,
 {
 	struct usb_device *dev = chip->dev;
 	unsigned char data[1];
-	unsigned int ep;
 	int err;
 
-	ep = get_endpoint(alts, 0)->bEndpointAddress;
-
 	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), 1000)) < 0) {
-		snd_printk(KERN_ERR "%d:%d:%d: cannot set enable PITCH (v2)\n",
-			   dev->devnum, iface, fmt->altsetting);
+				   data, sizeof(data))) < 0) {
+		usb_audio_err(chip, "%d:%d: cannot set enable PITCH (v2)\n",
+			      iface, fmt->altsetting);
 		return err;
 	}
 
@@ -166,13 +202,11 @@ int snd_usb_init_pitch(struct snd_usb_audio *chip, int iface,
 		       struct usb_host_interface *alts,
 		       struct audioformat *fmt)
 {
-	struct usb_interface_descriptor *altsd = get_iface_desc(alts);
-
 	/* if endpoint doesn't have pitch control, bail out */
 	if (!(fmt->attributes & UAC_EP_CS_ATTR_PITCH_CONTROL))
 		return 0;
 
-	switch (altsd->bInterfaceProtocol) {
+	switch (fmt->protocol) {
 	case UAC_VERSION_1:
 	default:
 		return init_pitch_v1(chip, iface, alts, fmt);
@@ -182,6 +216,234 @@ int snd_usb_init_pitch(struct snd_usb_audio *chip, int iface,
 	}
 }
 
+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
  */
@@ -191,8 +453,6 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 	struct usb_host_interface *alts;
 	struct usb_interface_descriptor *altsd;
 	struct usb_interface *iface;
-	unsigned int ep, attr;
-	int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
 	int err;
 
 	iface = usb_ifnum_to_if(dev, fmt->iface);
@@ -208,9 +468,11 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 
 	/* close the old interface */
 	if (subs->interface >= 0 && subs->interface != fmt->iface) {
-		if (usb_set_interface(subs->dev, subs->interface, 0) < 0) {
-			snd_printk(KERN_ERR "%d:%d:%d: return to setting 0 failed\n",
-				dev->devnum, fmt->iface, fmt->altsetting);
+		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;
@@ -218,100 +480,192 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 	}
 
 	/* set interface */
-	if (subs->interface != fmt->iface || subs->altset_idx != fmt->altset_idx) {
-		if (usb_set_interface(dev, fmt->iface, fmt->altsetting) < 0) {
-			snd_printk(KERN_ERR "%d:%d:%d: usb_set_interface failed\n",
-				   dev->devnum, fmt->iface, fmt->altsetting);
+	if (subs->interface != fmt->iface ||
+	    subs->altset_idx != fmt->altset_idx) {
+		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;
 		}
-		snd_printdd(KERN_INFO "setting usb interface %d:%d\n", fmt->iface, fmt->altsetting);
+		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);
 	}
 
-	/* create a data pipe */
-	ep = fmt->endpoint & USB_ENDPOINT_NUMBER_MASK;
-	if (is_playback)
-		subs->datapipe = usb_sndisocpipe(dev, ep);
-	else
-		subs->datapipe = usb_rcvisocpipe(dev, ep);
-	subs->datainterval = fmt->datainterval;
-	subs->syncpipe = subs->syncinterval = 0;
-	subs->maxpacksize = fmt->maxpacksize;
-	subs->syncmaxsize = 0;
-	subs->fill_max = 0;
+	subs->data_endpoint = snd_usb_add_endpoint(subs->stream->chip,
+						   alts, fmt->endpoint, subs->direction,
+						   SND_USB_ENDPOINT_TYPE_DATA);
 
-	/* 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;
-	if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) ||
-	     (! is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) &&
-	    altsd->bNumEndpoints >= 2) {
-		/* 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) != 0x01 ||
-		    (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
-		     get_endpoint(alts, 1)->bSynchAddress != 0)) {
-			snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
-				   dev->devnum, fmt->iface, fmt->altsetting);
-			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)))) {
-			snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
-				   dev->devnum, fmt->iface, fmt->altsetting);
-			return -EINVAL;
-		}
-		ep &= USB_ENDPOINT_NUMBER_MASK;
-		if (is_playback)
-			subs->syncpipe = usb_rcvisocpipe(dev, ep);
-		else
-			subs->syncpipe = usb_sndisocpipe(dev, ep);
-		if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
-		    get_endpoint(alts, 1)->bRefresh >= 1 &&
-		    get_endpoint(alts, 1)->bRefresh <= 9)
-			subs->syncinterval = get_endpoint(alts, 1)->bRefresh;
-		else if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
-			subs->syncinterval = 1;
-		else if (get_endpoint(alts, 1)->bInterval >= 1 &&
-			 get_endpoint(alts, 1)->bInterval <= 16)
-			subs->syncinterval = get_endpoint(alts, 1)->bInterval - 1;
-		else
-			subs->syncinterval = 3;
-		subs->syncmaxsize = le16_to_cpu(get_endpoint(alts, 1)->wMaxPacketSize);
-	}
+	if (!subs->data_endpoint)
+		return -EINVAL;
 
-	/* always fill max packet size */
-	if (fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX)
-		subs->fill_max = 1;
+	err = set_sync_endpoint(subs, fmt, dev, alts, altsd);
+	if (err < 0)
+		return err;
 
-	if ((err = snd_usb_init_pitch(subs->stream->chip, subs->interface, alts, fmt)) < 0)
+	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);
 
-#if 0
-	printk(KERN_DEBUG
-	       "setting done: format = %d, rate = %d..%d, channels = %d\n",
-	       fmt->format, fmt->rate_min, fmt->rate_max, fmt->channels);
-	printk(KERN_DEBUG
-	       "  datapipe = 0x%0x, syncpipe = 0x%0x\n",
-	       subs->datapipe, subs->syncpipe);
-#endif
-
 	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.
@@ -326,54 +680,42 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 {
 	struct snd_usb_substream *subs = substream->runtime->private_data;
 	struct audioformat *fmt;
-	unsigned int channels, rate, format;
-	int ret, changed;
+	int ret;
 
 	ret = snd_pcm_lib_alloc_vmalloc_buffer(substream,
 					       params_buffer_bytes(hw_params));
 	if (ret < 0)
 		return ret;
 
-	format = params_format(hw_params);
-	rate = params_rate(hw_params);
-	channels = params_channels(hw_params);
-	fmt = find_format(subs, format, rate, channels);
+	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) {
-		snd_printd(KERN_DEBUG "cannot set format: format = %#x, rate = %d, channels = %d\n",
-			   format, rate, channels);
+		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;
 	}
 
-	changed = subs->cur_audiofmt != fmt ||
-		subs->period_bytes != params_period_bytes(hw_params) ||
-		subs->cur_rate != rate;
-	if ((ret = set_format(subs, fmt)) < 0)
+	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;
 
-	if (subs->cur_rate != rate) {
-		struct usb_host_interface *alts;
-		struct usb_interface *iface;
-		iface = usb_ifnum_to_if(subs->dev, fmt->iface);
-		alts = &iface->altsetting[fmt->altset_idx];
-		ret = snd_usb_init_sample_rate(subs->stream->chip, subs->interface, alts, fmt, rate);
-		if (ret < 0)
-			return ret;
-		subs->cur_rate = rate;
-	}
+	subs->interface = fmt->iface;
+	subs->altset_idx = fmt->altset_idx;
+	subs->need_setup_ep = true;
 
-	if (changed) {
-		mutex_lock(&subs->stream->chip->shutdown_mutex);
-		/* format changed */
-		snd_usb_release_substream_urbs(subs, 0);
-		/* influenced: period_bytes, channels, rate, format, */
-		ret = snd_usb_init_substream_urbs(subs, params_period_bytes(hw_params),
-						  params_rate(hw_params),
-						  snd_pcm_format_physical_width(params_format(hw_params)) *
-							params_channels(hw_params));
-		mutex_unlock(&subs->stream->chip->shutdown_mutex);
-	}
-
-	return ret;
+	return 0;
 }
 
 /*
@@ -388,9 +730,13 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
 	subs->cur_audiofmt = NULL;
 	subs->cur_rate = 0;
 	subs->period_bytes = 0;
-	mutex_lock(&subs->stream->chip->shutdown_mutex);
-	snd_usb_release_substream_urbs(subs, 0);
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	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);
 }
 
@@ -403,23 +749,70 @@ 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) {
-		snd_printk(KERN_ERR "usbaudio: no format is specified!\n");
+		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->maxframesize = bytes_to_frames(runtime, subs->maxpacksize);
-	subs->curframesize = bytes_to_frames(runtime, subs->curpacksize);
+	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->phase = 0;
+	subs->last_delay = 0;
+	subs->last_frame_number = 0;
 	runtime->delay = 0;
 
-	return snd_usb_substream_prepare(subs, runtime);
+	/* 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 =
@@ -472,7 +865,7 @@ static int hw_check_valid_format(struct snd_usb_substream *subs,
 		return 0;
 	}
 	/* check whether the period time is >= the data packet interval */
-	if (snd_usb_get_speed(subs->dev) != USB_SPEED_FULL) {
+	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);
@@ -486,7 +879,7 @@ 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 list_head *p;
+	struct audioformat *fp;
 	struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
 	unsigned int rmin, rmax;
 	int changed;
@@ -494,9 +887,7 @@ static int hw_rule_rate(struct snd_pcm_hw_params *params,
 	hwc_debug("hw_rule_rate: (%d,%d)\n", it->min, it->max);
 	changed = 0;
 	rmin = rmax = 0;
-	list_for_each(p, &subs->fmt_list) {
-		struct audioformat *fp;
-		fp = list_entry(p, struct audioformat, list);
+	list_for_each_entry(fp, &subs->fmt_list, list) {
 		if (!hw_check_valid_format(subs, params, fp))
 			continue;
 		if (changed++) {
@@ -540,7 +931,7 @@ 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 list_head *p;
+	struct audioformat *fp;
 	struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
 	unsigned int rmin, rmax;
 	int changed;
@@ -548,9 +939,7 @@ static int hw_rule_channels(struct snd_pcm_hw_params *params,
 	hwc_debug("hw_rule_channels: (%d,%d)\n", it->min, it->max);
 	changed = 0;
 	rmin = rmax = 0;
-	list_for_each(p, &subs->fmt_list) {
-		struct audioformat *fp;
-		fp = list_entry(p, struct audioformat, list);
+	list_for_each_entry(fp, &subs->fmt_list, list) {
 		if (!hw_check_valid_format(subs, params, fp))
 			continue;
 		if (changed++) {
@@ -593,7 +982,7 @@ 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 list_head *p;
+	struct audioformat *fp;
 	struct snd_mask *fmt = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
 	u64 fbits;
 	u32 oldbits[2];
@@ -601,9 +990,7 @@ static int hw_rule_format(struct snd_pcm_hw_params *params,
 
 	hwc_debug("hw_rule_format: %x:%x\n", fmt->bits[0], fmt->bits[1]);
 	fbits = 0;
-	list_for_each(p, &subs->fmt_list) {
-		struct audioformat *fp;
-		fp = list_entry(p, struct audioformat, list);
+	list_for_each_entry(fp, &subs->fmt_list, list) {
 		if (!hw_check_valid_format(subs, params, fp))
 			continue;
 		fbits |= fp->formats;
@@ -667,9 +1054,13 @@ 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;
@@ -680,7 +1071,8 @@ static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
 	if (!needs_knot)
 		return 0;
 
-	subs->rate_list.list = kmalloc(sizeof(int) * count, GFP_KERNEL);
+	subs->rate_list.list = rate_list =
+		kmalloc(sizeof(int) * count, GFP_KERNEL);
 	if (!subs->rate_list.list)
 		return -ENOMEM;
 	subs->rate_list.count = count;
@@ -689,7 +1081,7 @@ static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
 	list_for_each_entry(fp, &subs->fmt_list, list) {
 		int i;
 		for (i = 0; i < fp->nr_rates; i++)
-			subs->rate_list.list[count++] = fp->rate_table[i];
+			rate_list[count++] = fp->rate_table[i];
 	}
 	err = snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
 					 &subs->rate_list);
@@ -706,7 +1098,7 @@ static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
 
 static int setup_hw_info(struct snd_pcm_runtime *runtime, struct snd_usb_substream *subs)
 {
-	struct list_head *p;
+	struct audioformat *fp;
 	unsigned int pt, ptmin;
 	int param_period_time_if_needed;
 	int err;
@@ -720,9 +1112,7 @@ static int setup_hw_info(struct snd_pcm_runtime *runtime, struct snd_usb_substre
 	runtime->hw.rates = 0;
 	ptmin = UINT_MAX;
 	/* check min/max rates and channels */
-	list_for_each(p, &subs->fmt_list) {
-		struct audioformat *fp;
-		fp = list_entry(p, struct audioformat, list);
+	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;
@@ -745,7 +1135,7 @@ static int setup_hw_info(struct snd_pcm_runtime *runtime, struct snd_usb_substre
 		return err;
 
 	param_period_time_if_needed = SNDRV_PCM_HW_PARAM_PERIOD_TIME;
-	if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
+	if (subs->speed == USB_SPEED_FULL)
 		/* full speed devices have fixed data packet interval */
 		ptmin = 1000;
 	if (ptmin == 1000)
@@ -807,6 +1197,12 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream, int direction)
 	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);
 }
 
@@ -815,15 +1211,313 @@ 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 */
+
+	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);
@@ -844,6 +1538,65 @@ 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:
+	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,