ALSA: snd-usb: switch over to new endpoint streaming logic

With the previous commit that added the new streaming model, all
endpoint and streaming related code is now in endpoint.c, and pcm.c
only acts as a wrapper for handling the packet's payload.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/card.c

@@ -131,8 +131,9 @@ static void snd_usb_stream_disconnect(struct list_head *head)
 		subs = &as->substream[idx];
 		if (!subs->num_formats)
 			continue;
-		snd_usb_release_substream_urbs(subs, 1);
 		subs->interface = -1;
+		subs->data_endpoint = NULL;
+		subs->sync_endpoint = NULL;
 	}
 }
 
@@ -350,6 +351,7 @@ static int snd_usb_audio_create(struct usb_device *dev, int idx,
 	chip->usb_id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
 			      le16_to_cpu(dev->descriptor.idProduct));
 	INIT_LIST_HEAD(&chip->pcm_list);
+	INIT_LIST_HEAD(&chip->ep_list);
 	INIT_LIST_HEAD(&chip->midi_list);
 	INIT_LIST_HEAD(&chip->mixer_list);
 
@@ -567,6 +569,10 @@ static void snd_usb_audio_disconnect(struct usb_device *dev,
 		list_for_each(p, &chip->pcm_list) {
 			snd_usb_stream_disconnect(p);
 		}
+		/* release the endpoint resources */
+		list_for_each(p, &chip->ep_list) {
+			snd_usb_endpoint_free(p);
+		}
 		/* release the midi resources */
 		list_for_each(p, &chip->midi_list) {
 			snd_usbmidi_disconnect(p);

sound/usb/card.h

@@ -145,6 +145,10 @@ struct snd_usb_substream {
 	struct snd_urb_ctx syncurb[SYNC_URBS];	/* sync urb table */
 	char *syncbuf;				/* sync buffer for all sync URBs */
 	dma_addr_t sync_dma;			/* DMA address of syncbuf */
+	/* data and sync endpoints for this stream */
+	struct snd_usb_endpoint *data_endpoint;
+	struct snd_usb_endpoint *sync_endpoint;
+	unsigned long flags;
 
 	u64 formats;			/* format bitmasks (all or'ed) */
 	unsigned int num_formats;		/* number of supported audio formats (list) */

sound/usb/endpoint.c

@@ -912,46 +912,6 @@ void snd_usb_init_substream(struct snd_usb_stream *as,
 	subs->fmt_type = fp->fmt_type;
 }
 
-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->ops.prepare = prepare_playback_urb;
-		return 0;
-	case SNDRV_PCM_TRIGGER_STOP:
-		return deactivate_urbs_old(subs, 0, 0);
-	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
-		subs->ops.prepare = prepare_nodata_playback_urb;
-		return 0;
-	}
-
-	return -EINVAL;
-}
-
-int snd_usb_substream_capture_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->ops.retire = retire_capture_urb;
-		return start_urbs(subs, substream->runtime);
-	case SNDRV_PCM_TRIGGER_STOP:
-		return deactivate_urbs_old(subs, 0, 0);
-	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
-		subs->ops.retire = retire_paused_capture_urb;
-		return 0;
-	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
-		subs->ops.retire = retire_capture_urb;
-		return 0;
-	}
-
-	return -EINVAL;
-}
-
 int snd_usb_substream_prepare(struct snd_usb_substream *subs,
 			      struct snd_pcm_runtime *runtime)
 {

sound/usb/endpoint.h

@@ -15,9 +15,6 @@ void snd_usb_release_substream_urbs(struct snd_usb_substream *subs, int force);
 int snd_usb_substream_prepare(struct snd_usb_substream *subs,
 			      struct snd_pcm_runtime *runtime);
 
-int snd_usb_substream_playback_trigger(struct snd_pcm_substream *substream, int cmd);
-int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream, int cmd);
-
 
 #define SND_USB_ENDPOINT_TYPE_DATA     0
 #define SND_USB_ENDPOINT_TYPE_SYNC     1

sound/usb/pcm.c

@@ -16,6 +16,7 @@
 
 #include <linux/init.h>
 #include <linux/slab.h>
+#include <linux/ratelimit.h>
 #include <linux/usb.h>
 #include <linux/usb/audio.h>
 #include <linux/usb/audio-v2.h>
@@ -34,6 +35,9 @@
 #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)
@@ -208,6 +212,84 @@ int snd_usb_init_pitch(struct snd_usb_audio *chip, int iface,
 	}
 }
 
+static int start_endpoints(struct snd_usb_substream *subs)
+{
+	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;
+
+		snd_printdd(KERN_DEBUG "Starting data EP @%p\n", ep);
+
+		ep->data_subs = subs;
+		err = snd_usb_endpoint_start(ep);
+		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;
+
+		snd_printdd(KERN_DEBUG "Starting sync EP @%p\n", ep);
+
+		ep->sync_slave = subs->data_endpoint;
+		err = snd_usb_endpoint_start(ep);
+		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,
+			   int force, int can_sleep, int wait)
+{
+	if (test_and_clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags))
+		snd_usb_endpoint_stop(subs->sync_endpoint,
+				      force, can_sleep, wait);
+
+	if (test_and_clear_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags))
+		snd_usb_endpoint_stop(subs->data_endpoint,
+				      force, can_sleep, wait);
+}
+
+static int activate_endpoints(struct snd_usb_substream *subs)
+{
+	if (subs->sync_endpoint) {
+		int ret;
+
+		ret = snd_usb_endpoint_activate(subs->sync_endpoint);
+		if (ret < 0)
+			return ret;
+	}
+
+	return snd_usb_endpoint_activate(subs->data_endpoint);
+}
+
+static int deactivate_endpoints(struct snd_usb_substream *subs)
+{
+	int reta, retb;
+
+	reta = snd_usb_endpoint_deactivate(subs->sync_endpoint);
+	retb = snd_usb_endpoint_deactivate(subs->data_endpoint);
+
+	if (reta < 0)
+		return reta;
+
+	if (retb < 0)
+		return retb;
+
+	return 0;
+}
+
 /*
  * find a matching format and set up the interface
  */
@@ -232,40 +314,11 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 	if (fmt == subs->cur_audiofmt)
 		return 0;
 
-	/* 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);
-			return -EIO;
-		}
-		subs->interface = -1;
-		subs->altset_idx = 0;
-	}
-
-	/* 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);
-			return -EIO;
-		}
-		snd_printdd(KERN_INFO "setting usb interface %d:%d\n", fmt->iface, fmt->altsetting);
-		subs->interface = fmt->iface;
-		subs->altset_idx = fmt->altset_idx;
-	}
-
-	/* 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);
+	if (!subs->data_endpoint)
+		return -EINVAL;
 
 	/* we need a sync pipe in async OUT or adaptive IN mode */
 	/* check the number of EP, since some devices have broken
@@ -276,6 +329,15 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 	if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) ||
 	     (! is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) &&
 	    altsd->bNumEndpoints >= 2) {
+		switch (subs->stream->chip->usb_id) {
+		case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
+		case USB_ID(0x0763, 0x2081):
+			ep = 0x81;
+			iface = usb_ifnum_to_if(dev, 2);
+			alts = &iface->altsetting[1];
+			goto add_sync_ep;
+		}
+
 		/* check sync-pipe endpoint */
 		/* ... and check descriptor size before accessing bSynchAddress
 		   because there is a version of the SB Audigy 2 NX firmware lacking
@@ -295,28 +357,16 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 				   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);
-	}
+add_sync_ep:
+		subs->sync_endpoint = snd_usb_add_endpoint(subs->stream->chip,
+							   alts, ep, !subs->direction,
+							   SND_USB_ENDPOINT_TYPE_SYNC);
 
-	/* always fill max packet size */
-	if (fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX)
-		subs->fill_max = 1;
+		if (!subs->sync_endpoint)
+			return -EINVAL;
+
+		subs->data_endpoint->sync_master = subs->sync_endpoint;
+	}
 
 	if ((err = snd_usb_init_pitch(subs->stream->chip, subs->interface, alts, fmt)) < 0)
 		return err;
@@ -390,12 +440,22 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 	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));
+		stop_endpoints(subs, 0, 0, 0);
+		deactivate_endpoints(subs);
+
+		ret = activate_endpoints(subs);
+		if (ret < 0)
+			goto unlock;
+
+		ret = snd_usb_endpoint_set_params(subs->data_endpoint, hw_params, fmt,
+						  subs->sync_endpoint);
+		if (ret < 0)
+			goto unlock;
+
+		if (subs->sync_endpoint)
+			ret = snd_usb_endpoint_set_params(subs->sync_endpoint,
+							  hw_params, fmt, NULL);
+unlock:
 		mutex_unlock(&subs->stream->chip->shutdown_mutex);
 	}
 
@@ -415,7 +475,7 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
 	subs->cur_rate = 0;
 	subs->period_bytes = 0;
 	mutex_lock(&subs->stream->chip->shutdown_mutex);
-	snd_usb_release_substream_urbs(subs, 0);
+	stop_endpoints(subs, 0, 1, 1);
 	mutex_unlock(&subs->stream->chip->shutdown_mutex);
 	return snd_pcm_lib_free_vmalloc_buffer(substream);
 }
@@ -435,19 +495,28 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
 		return -ENXIO;
 	}
 
+	if (snd_BUG_ON(!subs->data_endpoint))
+		return -EIO;
+
 	/* 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)
+		return start_endpoints(subs);
+
+	return 0;
 }
 
 static struct snd_pcm_hardware snd_usb_hardware =
@@ -842,16 +911,171 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream, int direction)
 
 static int snd_usb_pcm_close(struct snd_pcm_substream *substream, int direction)
 {
+	int ret;
 	struct snd_usb_stream *as = snd_pcm_substream_chip(substream);
 	struct snd_usb_substream *subs = &as->substream[direction];
 
-	if (!as->chip->shutdown && subs->interface >= 0) {
-		usb_set_interface(subs->dev, subs->interface, 0);
-		subs->interface = -1;
-	}
+	stop_endpoints(subs, 0, 0, 0);
+	ret = deactivate_endpoints(subs);
 	subs->pcm_substream = NULL;
 	snd_usb_autosuspend(subs->stream->chip);
-	return 0;
+
+	return ret;
+}
+
+/* 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;
+
+	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;
+		if (urb->iso_frame_desc[i].status && printk_ratelimit()) {
+			snd_printdd(KERN_ERR "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) {
+#ifdef CONFIG_SND_DEBUG_VERBOSE
+			int oldbytes = bytes;
+#endif
+			bytes = frames * stride;
+			snd_printdd(KERN_ERR "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;
+		}
+		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 void prepare_playback_urb(struct snd_usb_substream *subs,
+				 struct urb *urb)
+{
+	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;
+	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);
+	for (i = 0; i < ctx->packets; i++) {
+		counts = ctx->packet_size[i];
+		/* set up descriptor */
+		urb->iso_frame_desc[i].offset = frames * stride;
+		urb->iso_frame_desc[i].length = counts * stride;
+		frames += counts;
+		urb->number_of_packets++;
+		subs->transfer_done += counts;
+		if (subs->transfer_done >= runtime->period_size) {
+			subs->transfer_done -= runtime->period_size;
+			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 * stride;
+					subs->transfer_done = 0;
+				}
+				i++;
+				if (i < ctx->packets) {
+					/* add a transfer delimiter */
+					urb->iso_frame_desc[i].offset =
+						frames * stride;
+					urb->iso_frame_desc[i].length = 0;
+					urb->number_of_packets++;
+				}
+				break;
+			}
+		}
+		if (period_elapsed &&
+		    !snd_usb_endpoint_implict_feedback_sink(subs->data_endpoint)) /* finish at the period boundary */
+			break;
+	}
+	bytes = frames * stride;
+	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;
+	runtime->delay += frames;
+	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;
+	int stride = runtime->frame_bits >> 3;
+	int processed = urb->transfer_buffer_length / stride;
+
+	spin_lock_irqsave(&subs->lock, flags);
+	if (processed > runtime->delay)
+		runtime->delay = 0;
+	else
+		runtime->delay -= processed;
+	spin_unlock_irqrestore(&subs->lock, flags);
 }
 
 static int snd_usb_playback_open(struct snd_pcm_substream *substream)
@@ -874,6 +1098,56 @@ 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;
+		return 0;
+	case SNDRV_PCM_TRIGGER_STOP:
+		stop_endpoints(subs, 0, 0, 0);
+		return 0;
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		subs->data_endpoint->prepare_data_urb = NULL;
+		subs->data_endpoint->retire_data_urb = NULL;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+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);
+		if (err < 0)
+			return err;
+
+		subs->data_endpoint->retire_data_urb = retire_capture_urb;
+		return 0;
+	case SNDRV_PCM_TRIGGER_STOP:
+		stop_endpoints(subs, 0, 0, 0);
+		return 0;
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		subs->data_endpoint->retire_data_urb = NULL;
+		return 0;
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		subs->data_endpoint->retire_data_urb = retire_capture_urb;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 static struct snd_pcm_ops snd_usb_playback_ops = {
 	.open =		snd_usb_playback_open,
 	.close =	snd_usb_playback_close,

sound/usb/stream.c

@@ -73,6 +73,31 @@ static void snd_usb_audio_pcm_free(struct snd_pcm *pcm)
 	}
 }
 
+/*
+ * initialize the substream instance.
+ */
+
+static void snd_usb_init_substream(struct snd_usb_stream *as,
+				   int stream,
+				   struct audioformat *fp)
+{
+	struct snd_usb_substream *subs = &as->substream[stream];
+
+	INIT_LIST_HEAD(&subs->fmt_list);
+	spin_lock_init(&subs->lock);
+
+	subs->stream = as;
+	subs->direction = stream;
+	subs->dev = as->chip->dev;
+	subs->txfr_quirk = as->chip->txfr_quirk;
+
+	snd_usb_set_pcm_ops(as->pcm, stream);
+
+	list_add_tail(&fp->list, &subs->fmt_list);
+	subs->formats |= fp->formats;
+	subs->num_formats++;
+	subs->fmt_type = fp->fmt_type;
+}
 
 /*
  * add this endpoint to the chip instance.
@@ -94,9 +119,9 @@ int snd_usb_add_audio_stream(struct snd_usb_audio *chip,
 		if (as->fmt_type != fp->fmt_type)
 			continue;
 		subs = &as->substream[stream];
-		if (!subs->endpoint)
+		if (!subs->data_endpoint)
 			continue;
-		if (subs->endpoint == fp->endpoint) {
+		if (subs->data_endpoint->ep_num == fp->endpoint) {
 			list_add_tail(&fp->list, &subs->fmt_list);
 			subs->num_formats++;
 			subs->formats |= fp->formats;
@@ -109,7 +134,7 @@ int snd_usb_add_audio_stream(struct snd_usb_audio *chip,
 		if (as->fmt_type != fp->fmt_type)
 			continue;
 		subs = &as->substream[stream];
-		if (subs->endpoint)
+		if (subs->data_endpoint)
 			continue;
 		err = snd_pcm_new_stream(as->pcm, stream, 1);
 		if (err < 0)