Merge tag 'sound-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound

Pull sound updates from Takashi Iwai:
 "This is the first big chunk for 3.5 merges of sound stuff.

  There are a few big changes in different areas.  First off, the
  streaming logic of USB-audio endpoints has been largely rewritten for
  the better support of "implicit feedback".  If anything about USB got
  broken, this change has to be checked.

  For HD-audio, the resume procedure was changed; instead of delaying
  the resume of the hardware until the first use, now waking up
  immediately at resume.  This is for buggy BIOS.

  For ASoC, dynamic PCM support and the improved support for digital
  links between off-SoC devices are major framework changes.

  Some highlights are below:

  * HD-audio
   - Avoid accesses of invalid pin-control bits that may stall the codec
   - V-ref setup cleanups
   - Fix the races in power-saving code
   - Fix the races in codec cache hashes and connection lists
   - Split some common codes for BIOS auto-parser to hda_auto_parser.c
   - Changed the PM resume code to wake up immediately for buggy BIOS
   - Creative SoundCore3D support
   - Add Conexant CX20751/2/3/4 codec support

  * ASoC
   - Dynamic PCM support, allowing support for SoCs with internal
     routing through components with tight sequencing and formatting
     constraints within their internal paths or where there are multiple
     components connected with CPU managed DMA controllers inside the
     SoC.
   - Greatly improved support for direct digital links between off-SoC
     devices, providing a much simpler way of connecting things like
     digital basebands to CODECs.
   - Much more fine grained and robust locking, cleaning up some of the
     confusion that crept in with multi-component.
   - CPU support for nVidia Tegra 30 I2S and audio hub controllers and
     ST-Ericsson MSP I2S controolers
   - New CODEC drivers for Cirrus CS42L52, LAPIS Semiconductor ML26124,
     Texas Instruments LM49453.
   - Some regmap changes needed by the Tegra I2S driver.
   - mc13783 audio support.

  * Misc
   - Rewrite with module_pci_driver()
   - Xonar DGX support for snd-oxygen
   - Improvement of packet handling in snd-firewire driver
   - New USB-endpoint streaming logic
   - Enhanced M-audio FTU quirks and relevant cleanups
   - Increment the support of OSS devices to 256
   - snd-aloop accuracy improvement

  There are a few more pending changes for 3.5, but they will be sent
  slightly later as partly depending on the changes of DRM."

Fix up conflicts in regmap (due to duplicate patches, with some further
updates then having already come in from the regmap tree).  Also some
fairly trivial context conflicts in the imx and mcx soc drivers.

* tag 'sound-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (280 commits)
  ALSA: snd-usb: fix stream info output in /proc
  ALSA: pcm - Add proper state checks to snd_pcm_drain()
  ALSA: sh: Fix up namespace collision in sh_dac_audio.
  ALSA: hda/realtek - Fix unused variable compile warning
  ASoC: sh: fsi: enable chip specific data transfer mode
  ASoC: sh: fsi: call fsi_hw_startup/shutdown from fsi_dai_trigger()
  ASoC: sh: fsi: use same format for IN/OUT
  ASoC: sh: fsi: add fsi_version() and removed meaningless version check
  ASoC: sh: fsi: use register field macro name on IN/OUT_DMAC
  ASoC: tegra: Add machine driver for WM8753 codec
  ALSA: hda - Fix possible races of accesses to connection list array
  ASoC: OMAP: HDMI: Introduce codec
  ARM: mx31_3ds: Add sound support
  ASoC: imx-mc13783 cleanup
  mx31moboard: Add sound support
  ASoC: mc13783 codec cleanups
  ASoC: add imx-mc13783 sound support
  ASoC: Add mc13783 codec
  mfd: mc13xxx: add codec platform data
  ASoC: don't flip master of DT-instantiated DAI links
  ...

1 files changed, 902 insertions, 707 deletions

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 08dcce53720b..e6906901debb 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -20,9 +20,11 @@
 #include <linux/ratelimit.h>
 #include <linux/usb.h>
 #include <linux/usb/audio.h>
+#include <linux/slab.h>
 
 #include <sound/core.h>
 #include <sound/pcm.h>
+#include <sound/pcm_params.h>
 
 #include "usbaudio.h"
 #include "helper.h"
@@ -30,6 +32,36 @@
 #include "endpoint.h"
 #include "pcm.h"
 
+#define EP_FLAG_ACTIVATED	0
+#define EP_FLAG_RUNNING		1
+
+/*
+ * snd_usb_endpoint is a model that abstracts everything related to an
+ * USB endpoint and its streaming.
+ *
+ * There are functions to activate and deactivate the streaming URBs and
+ * optional callbacks to let the pcm logic handle the actual content of the
+ * packets for playback and record. Thus, the bus streaming and the audio
+ * handlers are fully decoupled.
+ *
+ * There are two different types of endpoints in audio applications.
+ *
+ * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
+ * inbound and outbound traffic.
+ *
+ * SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
+ * expect the payload to carry Q10.14 / Q16.16 formatted sync information
+ * (3 or 4 bytes).
+ *
+ * Each endpoint has to be configured prior to being used by calling
+ * snd_usb_endpoint_set_params().
+ *
+ * The model incorporates a reference counting, so that multiple users
+ * can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
+ * only the first user will effectively start the URBs, and only the last
+ * one to stop it will tear the URBs down again.
+ */
+
 /*
  * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
  * this will overflow at approx 524 kHz
@@ -49,71 +81,415 @@ static inline unsigned get_usb_high_speed_rate(unsigned int rate)
 }
 
 /*
- * unlink active urbs.
+ * release a urb data
  */
-static int deactivate_urbs(struct snd_usb_substream *subs, int force, int can_sleep)
+static void release_urb_ctx(struct snd_urb_ctx *u)
 {
-	struct snd_usb_audio *chip = subs->stream->chip;
-	unsigned int i;
-	int async;
+	if (u->buffer_size)
+		usb_free_coherent(u->ep->chip->dev, u->buffer_size,
+				  u->urb->transfer_buffer,
+				  u->urb->transfer_dma);
+	usb_free_urb(u->urb);
+	u->urb = NULL;
+}
+
+static const char *usb_error_string(int err)
+{
+	switch (err) {
+	case -ENODEV:
+		return "no device";
+	case -ENOENT:
+		return "endpoint not enabled";
+	case -EPIPE:
+		return "endpoint stalled";
+	case -ENOSPC:
+		return "not enough bandwidth";
+	case -ESHUTDOWN:
+		return "device disabled";
+	case -EHOSTUNREACH:
+		return "device suspended";
+	case -EINVAL:
+	case -EAGAIN:
+	case -EFBIG:
+	case -EMSGSIZE:
+		return "internal error";
+	default:
+		return "unknown error";
+	}
+}
+
+/**
+ * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
+ *
+ * @ep: The snd_usb_endpoint
+ *
+ * Determine whether an endpoint is driven by an implicit feedback
+ * data endpoint source.
+ */
+int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep)
+{
+	return  ep->sync_master &&
+		ep->sync_master->type == SND_USB_ENDPOINT_TYPE_DATA &&
+		ep->type == SND_USB_ENDPOINT_TYPE_DATA &&
+		usb_pipeout(ep->pipe);
+}
 
-	subs->running = 0;
+/*
+ * For streaming based on information derived from sync endpoints,
+ * prepare_outbound_urb_sizes() will call next_packet_size() to
+ * determine the number of samples to be sent in the next packet.
+ *
+ * For implicit feedback, next_packet_size() is unused.
+ */
+static int next_packet_size(struct snd_usb_endpoint *ep)
+{
+	unsigned long flags;
+	int ret;
 
-	if (!force && subs->stream->chip->shutdown) /* to be sure... */
-		return -EBADFD;
+	if (ep->fill_max)
+		return ep->maxframesize;
 
-	async = !can_sleep && chip->async_unlink;
+	spin_lock_irqsave(&ep->lock, flags);
+	ep->phase = (ep->phase & 0xffff)
+		+ (ep->freqm << ep->datainterval);
+	ret = min(ep->phase >> 16, ep->maxframesize);
+	spin_unlock_irqrestore(&ep->lock, flags);
 
-	if (!async && in_interrupt())
-		return 0;
+	return ret;
+}
 
-	for (i = 0; i < subs->nurbs; i++) {
-		if (test_bit(i, &subs->active_mask)) {
-			if (!test_and_set_bit(i, &subs->unlink_mask)) {
-				struct urb *u = subs->dataurb[i].urb;
-				if (async)
-					usb_unlink_urb(u);
-				else
-					usb_kill_urb(u);
+static void retire_outbound_urb(struct snd_usb_endpoint *ep,
+				struct snd_urb_ctx *urb_ctx)
+{
+	if (ep->retire_data_urb)
+		ep->retire_data_urb(ep->data_subs, urb_ctx->urb);
+}
+
+static void retire_inbound_urb(struct snd_usb_endpoint *ep,
+			       struct snd_urb_ctx *urb_ctx)
+{
+	struct urb *urb = urb_ctx->urb;
+
+	if (ep->sync_slave)
+		snd_usb_handle_sync_urb(ep->sync_slave, ep, urb);
+
+	if (ep->retire_data_urb)
+		ep->retire_data_urb(ep->data_subs, urb);
+}
+
+static void prepare_outbound_urb_sizes(struct snd_usb_endpoint *ep,
+				       struct snd_urb_ctx *ctx)
+{
+	int i;
+
+	for (i = 0; i < ctx->packets; ++i)
+		ctx->packet_size[i] = next_packet_size(ep);
+}
+
+/*
+ * Prepare a PLAYBACK urb for submission to the bus.
+ */
+static void prepare_outbound_urb(struct snd_usb_endpoint *ep,
+				 struct snd_urb_ctx *ctx)
+{
+	int i;
+	struct urb *urb = ctx->urb;
+	unsigned char *cp = urb->transfer_buffer;
+
+	urb->dev = ep->chip->dev; /* we need to set this at each time */
+
+	switch (ep->type) {
+	case SND_USB_ENDPOINT_TYPE_DATA:
+		if (ep->prepare_data_urb) {
+			ep->prepare_data_urb(ep->data_subs, urb);
+		} else {
+			/* no data provider, so send silence */
+			unsigned int offs = 0;
+			for (i = 0; i < ctx->packets; ++i) {
+				int counts = ctx->packet_size[i];
+				urb->iso_frame_desc[i].offset = offs * ep->stride;
+				urb->iso_frame_desc[i].length = counts * ep->stride;
+				offs += counts;
 			}
+
+			urb->number_of_packets = ctx->packets;
+			urb->transfer_buffer_length = offs * ep->stride;
+			memset(urb->transfer_buffer, ep->silence_value,
+			       offs * ep->stride);
 		}
+		break;
+
+	case SND_USB_ENDPOINT_TYPE_SYNC:
+		if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
+			/*
+			 * fill the length and offset of each urb descriptor.
+			 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
+			 */
+			urb->iso_frame_desc[0].length = 4;
+			urb->iso_frame_desc[0].offset = 0;
+			cp[0] = ep->freqn;
+			cp[1] = ep->freqn >> 8;
+			cp[2] = ep->freqn >> 16;
+			cp[3] = ep->freqn >> 24;
+		} else {
+			/*
+			 * fill the length and offset of each urb descriptor.
+			 * the fixed 10.14 frequency is passed through the pipe.
+			 */
+			urb->iso_frame_desc[0].length = 3;
+			urb->iso_frame_desc[0].offset = 0;
+			cp[0] = ep->freqn >> 2;
+			cp[1] = ep->freqn >> 10;
+			cp[2] = ep->freqn >> 18;
+		}
+
+		break;
 	}
-	if (subs->syncpipe) {
-		for (i = 0; i < SYNC_URBS; i++) {
-			if (test_bit(i+16, &subs->active_mask)) {
-				if (!test_and_set_bit(i+16, &subs->unlink_mask)) {
-					struct urb *u = subs->syncurb[i].urb;
-					if (async)
-						usb_unlink_urb(u);
-					else
-						usb_kill_urb(u);
-				}
-			}
+}
+
+/*
+ * Prepare a CAPTURE or SYNC urb for submission to the bus.
+ */
+static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep,
+				       struct snd_urb_ctx *urb_ctx)
+{
+	int i, offs;
+	struct urb *urb = urb_ctx->urb;
+
+	urb->dev = ep->chip->dev; /* we need to set this at each time */
+
+	switch (ep->type) {
+	case SND_USB_ENDPOINT_TYPE_DATA:
+		offs = 0;
+		for (i = 0; i < urb_ctx->packets; i++) {
+			urb->iso_frame_desc[i].offset = offs;
+			urb->iso_frame_desc[i].length = ep->curpacksize;
+			offs += ep->curpacksize;
 		}
+
+		urb->transfer_buffer_length = offs;
+		urb->number_of_packets = urb_ctx->packets;
+		break;
+
+	case SND_USB_ENDPOINT_TYPE_SYNC:
+		urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
+		urb->iso_frame_desc[0].offset = 0;
+		break;
 	}
-	return 0;
 }
 
+/*
+ * Send output urbs that have been prepared previously. URBs are dequeued
+ * from ep->ready_playback_urbs and in case there there aren't any available
+ * or there are no packets that have been prepared, this function does
+ * nothing.
+ *
+ * The reason why the functionality of sending and preparing URBs is separated
+ * is that host controllers don't guarantee the order in which they return
+ * inbound and outbound packets to their submitters.
+ *
+ * This function is only used for implicit feedback endpoints. For endpoints
+ * driven by dedicated sync endpoints, URBs are immediately re-submitted
+ * from their completion handler.
+ */
+static void queue_pending_output_urbs(struct snd_usb_endpoint *ep)
+{
+	while (test_bit(EP_FLAG_RUNNING, &ep->flags)) {
+
+		unsigned long flags;
+		struct snd_usb_packet_info *uninitialized_var(packet);
+		struct snd_urb_ctx *ctx = NULL;
+		struct urb *urb;
+		int err, i;
+
+		spin_lock_irqsave(&ep->lock, flags);
+		if (ep->next_packet_read_pos != ep->next_packet_write_pos) {
+			packet = ep->next_packet + ep->next_packet_read_pos;
+			ep->next_packet_read_pos++;
+			ep->next_packet_read_pos %= MAX_URBS;
+
+			/* take URB out of FIFO */
+			if (!list_empty(&ep->ready_playback_urbs))
+				ctx = list_first_entry(&ep->ready_playback_urbs,
+					       struct snd_urb_ctx, ready_list);
+		}
+		spin_unlock_irqrestore(&ep->lock, flags);
+
+		if (ctx == NULL)
+			return;
+
+		list_del_init(&ctx->ready_list);
+		urb = ctx->urb;
+
+		/* copy over the length information */
+		for (i = 0; i < packet->packets; i++)
+			ctx->packet_size[i] = packet->packet_size[i];
+
+		/* call the data handler to fill in playback data */
+		prepare_outbound_urb(ep, ctx);
+
+		err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
+		if (err < 0)
+			snd_printk(KERN_ERR "Unable to submit urb #%d: %d (urb %p)\n",
+				   ctx->index, err, ctx->urb);
+		else
+			set_bit(ctx->index, &ep->active_mask);
+	}
+}
 
 /*
- * release a urb data
+ * complete callback for urbs
  */
-static void release_urb_ctx(struct snd_urb_ctx *u)
+static void snd_complete_urb(struct urb *urb)
+{
+	struct snd_urb_ctx *ctx = urb->context;
+	struct snd_usb_endpoint *ep = ctx->ep;
+	int err;
+
+	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
+		     urb->status == -ENODEV ||		/* device removed */
+		     urb->status == -ECONNRESET ||	/* unlinked */
+		     urb->status == -ESHUTDOWN ||	/* device disabled */
+		     ep->chip->shutdown))		/* device disconnected */
+		goto exit_clear;
+
+	if (usb_pipeout(ep->pipe)) {
+		retire_outbound_urb(ep, ctx);
+		/* can be stopped during retire callback */
+		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
+			goto exit_clear;
+
+		if (snd_usb_endpoint_implict_feedback_sink(ep)) {
+			unsigned long flags;
+
+			spin_lock_irqsave(&ep->lock, flags);
+			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
+			spin_unlock_irqrestore(&ep->lock, flags);
+			queue_pending_output_urbs(ep);
+
+			goto exit_clear;
+		}
+
+		prepare_outbound_urb_sizes(ep, ctx);
+		prepare_outbound_urb(ep, ctx);
+	} else {
+		retire_inbound_urb(ep, ctx);
+		/* can be stopped during retire callback */
+		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
+			goto exit_clear;
+
+		prepare_inbound_urb(ep, ctx);
+	}
+
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+	if (err == 0)
+		return;
+
+	snd_printk(KERN_ERR "cannot submit urb (err = %d)\n", err);
+	//snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
+
+exit_clear:
+	clear_bit(ctx->index, &ep->active_mask);
+}
+
+/**
+ * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
+ *
+ * @chip: The chip
+ * @alts: The USB host interface
+ * @ep_num: The number of the endpoint to use
+ * @direction: SNDRV_PCM_STREAM_PLAYBACK or SNDRV_PCM_STREAM_CAPTURE
+ * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
+ *
+ * If the requested endpoint has not been added to the given chip before,
+ * a new instance is created. Otherwise, a pointer to the previoulsy
+ * created instance is returned. In case of any error, NULL is returned.
+ *
+ * New endpoints will be added to chip->ep_list and must be freed by
+ * calling snd_usb_endpoint_free().
+ */
+struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip,
+					      struct usb_host_interface *alts,
+					      int ep_num, int direction, int type)
 {
-	if (u->urb) {
-		if (u->buffer_size)
-			usb_free_coherent(u->subs->dev, u->buffer_size,
-					u->urb->transfer_buffer,
-					u->urb->transfer_dma);
-		usb_free_urb(u->urb);
-		u->urb = NULL;
+	struct list_head *p;
+	struct snd_usb_endpoint *ep;
+	int ret, is_playback = direction == SNDRV_PCM_STREAM_PLAYBACK;
+
+	mutex_lock(&chip->mutex);
+
+	list_for_each(p, &chip->ep_list) {
+		ep = list_entry(p, struct snd_usb_endpoint, list);
+		if (ep->ep_num == ep_num &&
+		    ep->iface == alts->desc.bInterfaceNumber &&
+		    ep->alt_idx == alts->desc.bAlternateSetting) {
+			snd_printdd(KERN_DEBUG "Re-using EP %x in iface %d,%d @%p\n",
+					ep_num, ep->iface, ep->alt_idx, ep);
+			goto __exit_unlock;
+		}
+	}
+
+	snd_printdd(KERN_DEBUG "Creating new %s %s endpoint #%x\n",
+		    is_playback ? "playback" : "capture",
+		    type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync",
+		    ep_num);
+
+	/* select the alt setting once so the endpoints become valid */
+	ret = usb_set_interface(chip->dev, alts->desc.bInterfaceNumber,
+				alts->desc.bAlternateSetting);
+	if (ret < 0) {
+		snd_printk(KERN_ERR "%s(): usb_set_interface() failed, ret = %d\n",
+					__func__, ret);
+		ep = NULL;
+		goto __exit_unlock;
 	}
+
+	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
+	if (!ep)
+		goto __exit_unlock;
+
+	ep->chip = chip;
+	spin_lock_init(&ep->lock);
+	ep->type = type;
+	ep->ep_num = ep_num;
+	ep->iface = alts->desc.bInterfaceNumber;
+	ep->alt_idx = alts->desc.bAlternateSetting;
+	INIT_LIST_HEAD(&ep->ready_playback_urbs);
+	ep_num &= USB_ENDPOINT_NUMBER_MASK;
+
+	if (is_playback)
+		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
+	else
+		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
+
+	if (type == SND_USB_ENDPOINT_TYPE_SYNC) {
+		if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+		    get_endpoint(alts, 1)->bRefresh >= 1 &&
+		    get_endpoint(alts, 1)->bRefresh <= 9)
+			ep->syncinterval = get_endpoint(alts, 1)->bRefresh;
+		else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
+			ep->syncinterval = 1;
+		else if (get_endpoint(alts, 1)->bInterval >= 1 &&
+			 get_endpoint(alts, 1)->bInterval <= 16)
+			ep->syncinterval = get_endpoint(alts, 1)->bInterval - 1;
+		else
+			ep->syncinterval = 3;
+
+		ep->syncmaxsize = le16_to_cpu(get_endpoint(alts, 1)->wMaxPacketSize);
+	}
+
+	list_add_tail(&ep->list, &chip->ep_list);
+
+__exit_unlock:
+	mutex_unlock(&chip->mutex);
+
+	return ep;
 }
 
 /*
  *  wait until all urbs are processed.
  */
-static int wait_clear_urbs(struct snd_usb_substream *subs)
+static int wait_clear_urbs(struct snd_usb_endpoint *ep)
 {
 	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
 	unsigned int i;
@@ -121,153 +497,148 @@ static int wait_clear_urbs(struct snd_usb_substream *subs)
 
 	do {
 		alive = 0;
-		for (i = 0; i < subs->nurbs; i++) {
-			if (test_bit(i, &subs->active_mask))
+		for (i = 0; i < ep->nurbs; i++)
+			if (test_bit(i, &ep->active_mask))
 				alive++;
-		}
-		if (subs->syncpipe) {
-			for (i = 0; i < SYNC_URBS; i++) {
-				if (test_bit(i + 16, &subs->active_mask))
-					alive++;
-			}
-		}
-		if (! alive)
+
+		if (!alive)
 			break;
+
 		schedule_timeout_uninterruptible(1);
 	} while (time_before(jiffies, end_time));
+
 	if (alive)
-		snd_printk(KERN_ERR "timeout: still %d active urbs..\n", alive);
+		snd_printk(KERN_ERR "timeout: still %d active urbs on EP #%x\n",
+					alive, ep->ep_num);
+
 	return 0;
 }
 
 /*
- * release a substream
+ * unlink active urbs.
  */
-void snd_usb_release_substream_urbs(struct snd_usb_substream *subs, int force)
+static int deactivate_urbs(struct snd_usb_endpoint *ep, int force, int can_sleep)
 {
-	int i;
+	unsigned int i;
+	int async;
 
-	/* stop urbs (to be sure) */
-	deactivate_urbs(subs, force, 1);
-	wait_clear_urbs(subs);
-
-	for (i = 0; i < MAX_URBS; i++)
-		release_urb_ctx(&subs->dataurb[i]);
-	for (i = 0; i < SYNC_URBS; i++)
-		release_urb_ctx(&subs->syncurb[i]);
-	usb_free_coherent(subs->dev, SYNC_URBS * 4,
-			subs->syncbuf, subs->sync_dma);
-	subs->syncbuf = NULL;
-	subs->nurbs = 0;
-}
+	if (!force && ep->chip->shutdown) /* to be sure... */
+		return -EBADFD;
 
-/*
- * complete callback from data urb
- */
-static void snd_complete_urb(struct urb *urb)
-{
-	struct snd_urb_ctx *ctx = urb->context;
-	struct snd_usb_substream *subs = ctx->subs;
-	struct snd_pcm_substream *substream = ctx->subs->pcm_substream;
-	int err = 0;
-
-	if ((subs->running && subs->ops.retire(subs, substream->runtime, urb)) ||
-	    !subs->running || /* can be stopped during retire callback */
-	    (err = subs->ops.prepare(subs, substream->runtime, urb)) < 0 ||
-	    (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
-		clear_bit(ctx->index, &subs->active_mask);
-		if (err < 0) {
-			snd_printd(KERN_ERR "cannot submit urb (err = %d)\n", err);
-			snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
+	async = !can_sleep && ep->chip->async_unlink;
+
+	clear_bit(EP_FLAG_RUNNING, &ep->flags);
+
+	INIT_LIST_HEAD(&ep->ready_playback_urbs);
+	ep->next_packet_read_pos = 0;
+	ep->next_packet_write_pos = 0;
+
+	if (!async && in_interrupt())
+		return 0;
+
+	for (i = 0; i < ep->nurbs; i++) {
+		if (test_bit(i, &ep->active_mask)) {
+			if (!test_and_set_bit(i, &ep->unlink_mask)) {
+				struct urb *u = ep->urb[i].urb;
+				if (async)
+					usb_unlink_urb(u);
+				else
+					usb_kill_urb(u);
+			}
 		}
 	}
-}
 
+	return 0;
+}
 
 /*
- * complete callback from sync urb
+ * release an endpoint's urbs
  */
-static void snd_complete_sync_urb(struct urb *urb)
+static void release_urbs(struct snd_usb_endpoint *ep, int force)
 {
-	struct snd_urb_ctx *ctx = urb->context;
-	struct snd_usb_substream *subs = ctx->subs;
-	struct snd_pcm_substream *substream = ctx->subs->pcm_substream;
-	int err = 0;
-
-	if ((subs->running && subs->ops.retire_sync(subs, substream->runtime, urb)) ||
-	    !subs->running || /* can be stopped during retire callback */
-	    (err = subs->ops.prepare_sync(subs, substream->runtime, urb)) < 0 ||
-	    (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
-		clear_bit(ctx->index + 16, &subs->active_mask);
-		if (err < 0) {
-			snd_printd(KERN_ERR "cannot submit sync urb (err = %d)\n", err);
-			snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
-		}
-	}
-}
+	int i;
 
+	/* route incoming urbs to nirvana */
+	ep->retire_data_urb = NULL;
+	ep->prepare_data_urb = NULL;
+
+	/* stop urbs */
+	deactivate_urbs(ep, force, 1);
+	wait_clear_urbs(ep);
+
+	for (i = 0; i < ep->nurbs; i++)
+		release_urb_ctx(&ep->urb[i]);
+
+	if (ep->syncbuf)
+		usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
+				  ep->syncbuf, ep->sync_dma);
+
+	ep->syncbuf = NULL;
+	ep->nurbs = 0;
+}
 
 /*
- * initialize a substream for plaback/capture
+ * configure a data endpoint
  */
-int snd_usb_init_substream_urbs(struct snd_usb_substream *subs,
-				unsigned int period_bytes,
-				unsigned int rate,
-				unsigned int frame_bits)
+static int data_ep_set_params(struct snd_usb_endpoint *ep,
+			      struct snd_pcm_hw_params *hw_params,
+			      struct audioformat *fmt,
+			      struct snd_usb_endpoint *sync_ep)
 {
-	unsigned int maxsize, i;
-	int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
-	unsigned int urb_packs, total_packs, packs_per_ms;
-	struct snd_usb_audio *chip = subs->stream->chip;
+	unsigned int maxsize, i, urb_packs, total_packs, packs_per_ms;
+	int period_bytes = params_period_bytes(hw_params);
+	int format = params_format(hw_params);
+	int is_playback = usb_pipeout(ep->pipe);
+	int frame_bits = snd_pcm_format_physical_width(params_format(hw_params)) *
+							params_channels(hw_params);
+
+	ep->datainterval = fmt->datainterval;
+	ep->stride = frame_bits >> 3;
+	ep->silence_value = format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0;
 
-	/* calculate the frequency in 16.16 format */
-	if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
-		subs->freqn = get_usb_full_speed_rate(rate);
-	else
-		subs->freqn = get_usb_high_speed_rate(rate);
-	subs->freqm = subs->freqn;
-	subs->freqshift = INT_MIN;
 	/* calculate max. frequency */
-	if (subs->maxpacksize) {
+	if (ep->maxpacksize) {
 		/* whatever fits into a max. size packet */
-		maxsize = subs->maxpacksize;
-		subs->freqmax = (maxsize / (frame_bits >> 3))
-				<< (16 - subs->datainterval);
+		maxsize = ep->maxpacksize;
+		ep->freqmax = (maxsize / (frame_bits >> 3))
+				<< (16 - ep->datainterval);
 	} else {
 		/* no max. packet size: just take 25% higher than nominal */
-		subs->freqmax = subs->freqn + (subs->freqn >> 2);
-		maxsize = ((subs->freqmax + 0xffff) * (frame_bits >> 3))
-				>> (16 - subs->datainterval);
+		ep->freqmax = ep->freqn + (ep->freqn >> 2);
+		maxsize = ((ep->freqmax + 0xffff) * (frame_bits >> 3))
+				>> (16 - ep->datainterval);
 	}
-	subs->phase = 0;
 
-	if (subs->fill_max)
-		subs->curpacksize = subs->maxpacksize;
+	if (ep->fill_max)
+		ep->curpacksize = ep->maxpacksize;
 	else
-		subs->curpacksize = maxsize;
+		ep->curpacksize = maxsize;
 
-	if (snd_usb_get_speed(subs->dev) != USB_SPEED_FULL)
-		packs_per_ms = 8 >> subs->datainterval;
+	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL)
+		packs_per_ms = 8 >> ep->datainterval;
 	else
 		packs_per_ms = 1;
 
-	if (is_playback) {
-		urb_packs = max(chip->nrpacks, 1);
-		urb_packs = min(urb_packs, (unsigned int)MAX_PACKS);
-	} else
+	if (is_playback && !snd_usb_endpoint_implict_feedback_sink(ep)) {
+		urb_packs = max(ep->chip->nrpacks, 1);
+		urb_packs = min(urb_packs, (unsigned int) MAX_PACKS);
+	} else {
 		urb_packs = 1;
+	}
+
 	urb_packs *= packs_per_ms;
-	if (subs->syncpipe)
-		urb_packs = min(urb_packs, 1U << subs->syncinterval);
+
+	if (sync_ep && !snd_usb_endpoint_implict_feedback_sink(ep))
+		urb_packs = min(urb_packs, 1U << sync_ep->syncinterval);
 
 	/* decide how many packets to be used */
-	if (is_playback) {
+	if (is_playback && !snd_usb_endpoint_implict_feedback_sink(ep)) {
 		unsigned int minsize, maxpacks;
 		/* determine how small a packet can be */
-		minsize = (subs->freqn >> (16 - subs->datainterval))
+		minsize = (ep->freqn >> (16 - ep->datainterval))
 			  * (frame_bits >> 3);
 		/* with sync from device, assume it can be 12% lower */
-		if (subs->syncpipe)
+		if (sync_ep)
 			minsize -= minsize >> 3;
 		minsize = max(minsize, 1u);
 		total_packs = (period_bytes + minsize - 1) / minsize;
@@ -284,284 +655,472 @@ int snd_usb_init_substream_urbs(struct snd_usb_substream *subs,
 			urb_packs >>= 1;
 		total_packs = MAX_URBS * urb_packs;
 	}
-	subs->nurbs = (total_packs + urb_packs - 1) / urb_packs;
-	if (subs->nurbs > MAX_URBS) {
+
+	ep->nurbs = (total_packs + urb_packs - 1) / urb_packs;
+	if (ep->nurbs > MAX_URBS) {
 		/* too much... */
-		subs->nurbs = MAX_URBS;
+		ep->nurbs = MAX_URBS;
 		total_packs = MAX_URBS * urb_packs;
-	} else if (subs->nurbs < 2) {
+	} else if (ep->nurbs < 2) {
 		/* too little - we need at least two packets
 		 * to ensure contiguous playback/capture
 		 */
-		subs->nurbs = 2;
+		ep->nurbs = 2;
 	}
 
 	/* allocate and initialize data urbs */
-	for (i = 0; i < subs->nurbs; i++) {
-		struct snd_urb_ctx *u = &subs->dataurb[i];
+	for (i = 0; i < ep->nurbs; i++) {
+		struct snd_urb_ctx *u = &ep->urb[i];
 		u->index = i;
-		u->subs = subs;
-		u->packets = (i + 1) * total_packs / subs->nurbs
-			- i * total_packs / subs->nurbs;
+		u->ep = ep;
+		u->packets = (i + 1) * total_packs / ep->nurbs
+			- i * total_packs / ep->nurbs;
 		u->buffer_size = maxsize * u->packets;
-		if (subs->fmt_type == UAC_FORMAT_TYPE_II)
+
+		if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
 			u->packets++; /* for transfer delimiter */
 		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
 		if (!u->urb)
 			goto out_of_memory;
+
 		u->urb->transfer_buffer =
-			usb_alloc_coherent(subs->dev, u->buffer_size,
+			usb_alloc_coherent(ep->chip->dev, u->buffer_size,
 					   GFP_KERNEL, &u->urb->transfer_dma);
 		if (!u->urb->transfer_buffer)
 			goto out_of_memory;
-		u->urb->pipe = subs->datapipe;
+		u->urb->pipe = ep->pipe;
 		u->urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
-		u->urb->interval = 1 << subs->datainterval;
+		u->urb->interval = 1 << ep->datainterval;
 		u->urb->context = u;
 		u->urb->complete = snd_complete_urb;
+		INIT_LIST_HEAD(&u->ready_list);
 	}
 
-	if (subs->syncpipe) {
-		/* allocate and initialize sync urbs */
-		subs->syncbuf = usb_alloc_coherent(subs->dev, SYNC_URBS * 4,
-						 GFP_KERNEL, &subs->sync_dma);
-		if (!subs->syncbuf)
-			goto out_of_memory;
-		for (i = 0; i < SYNC_URBS; i++) {
-			struct snd_urb_ctx *u = &subs->syncurb[i];
-			u->index = i;
-			u->subs = subs;
-			u->packets = 1;
-			u->urb = usb_alloc_urb(1, GFP_KERNEL);
-			if (!u->urb)
-				goto out_of_memory;
-			u->urb->transfer_buffer = subs->syncbuf + i * 4;
-			u->urb->transfer_dma = subs->sync_dma + i * 4;
-			u->urb->transfer_buffer_length = 4;
-			u->urb->pipe = subs->syncpipe;
-			u->urb->transfer_flags = URB_ISO_ASAP |
-						 URB_NO_TRANSFER_DMA_MAP;
-			u->urb->number_of_packets = 1;
-			u->urb->interval = 1 << subs->syncinterval;
-			u->urb->context = u;
-			u->urb->complete = snd_complete_sync_urb;
-		}
-	}
 	return 0;
 
 out_of_memory:
-	snd_usb_release_substream_urbs(subs, 0);
+	release_urbs(ep, 0);
 	return -ENOMEM;
 }
 
 /*
- * prepare urb for full speed capture sync pipe
- *
- * fill the length and offset of each urb descriptor.
- * the fixed 10.14 frequency is passed through the pipe.
+ * configure a sync endpoint
  */
-static int prepare_capture_sync_urb(struct snd_usb_substream *subs,
-				    struct snd_pcm_runtime *runtime,
-				    struct urb *urb)
+static int sync_ep_set_params(struct snd_usb_endpoint *ep,
+			      struct snd_pcm_hw_params *hw_params,
+			      struct audioformat *fmt)
 {
-	unsigned char *cp = urb->transfer_buffer;
-	struct snd_urb_ctx *ctx = urb->context;
+	int i;
+
+	ep->syncbuf = usb_alloc_coherent(ep->chip->dev, SYNC_URBS * 4,
+					 GFP_KERNEL, &ep->sync_dma);
+	if (!ep->syncbuf)
+		return -ENOMEM;
+
+	for (i = 0; i < SYNC_URBS; i++) {
+		struct snd_urb_ctx *u = &ep->urb[i];
+		u->index = i;
+		u->ep = ep;
+		u->packets = 1;
+		u->urb = usb_alloc_urb(1, GFP_KERNEL);
+		if (!u->urb)
+			goto out_of_memory;
+		u->urb->transfer_buffer = ep->syncbuf + i * 4;
+		u->urb->transfer_dma = ep->sync_dma + i * 4;
+		u->urb->transfer_buffer_length = 4;
+		u->urb->pipe = ep->pipe;
+		u->urb->transfer_flags = URB_ISO_ASAP |
+					 URB_NO_TRANSFER_DMA_MAP;
+		u->urb->number_of_packets = 1;
+		u->urb->interval = 1 << ep->syncinterval;
+		u->urb->context = u;
+		u->urb->complete = snd_complete_urb;
+	}
+
+	ep->nurbs = SYNC_URBS;
 
-	urb->dev = ctx->subs->dev; /* we need to set this at each time */
-	urb->iso_frame_desc[0].length = 3;
-	urb->iso_frame_desc[0].offset = 0;
-	cp[0] = subs->freqn >> 2;
-	cp[1] = subs->freqn >> 10;
-	cp[2] = subs->freqn >> 18;
 	return 0;
+
+out_of_memory:
+	release_urbs(ep, 0);
+	return -ENOMEM;
 }
 
-/*
- * prepare urb for high speed capture sync pipe
+/**
+ * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
+ *
+ * @ep: the snd_usb_endpoint to configure
+ * @hw_params: the hardware parameters
+ * @fmt: the USB audio format information
+ * @sync_ep: the sync endpoint to use, if any
  *
- * fill the length and offset of each urb descriptor.
- * the fixed 12.13 frequency is passed as 16.16 through the pipe.
+ * Determine the number of URBs to be used on this endpoint.
+ * An endpoint must be configured before it can be started.
+ * An endpoint that is already running can not be reconfigured.
  */
-static int prepare_capture_sync_urb_hs(struct snd_usb_substream *subs,
-				       struct snd_pcm_runtime *runtime,
-				       struct urb *urb)
+int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
+				struct snd_pcm_hw_params *hw_params,
+				struct audioformat *fmt,
+				struct snd_usb_endpoint *sync_ep)
 {
-	unsigned char *cp = urb->transfer_buffer;
-	struct snd_urb_ctx *ctx = urb->context;
+	int err;
 
-	urb->dev = ctx->subs->dev; /* we need to set this at each time */
-	urb->iso_frame_desc[0].length = 4;
-	urb->iso_frame_desc[0].offset = 0;
-	cp[0] = subs->freqn;
-	cp[1] = subs->freqn >> 8;
-	cp[2] = subs->freqn >> 16;
-	cp[3] = subs->freqn >> 24;
-	return 0;
+	if (ep->use_count != 0) {
+		snd_printk(KERN_WARNING "Unable to change format on ep #%x: already in use\n",
+			   ep->ep_num);
+		return -EBUSY;
+	}
+
+	/* release old buffers, if any */
+	release_urbs(ep, 0);
+
+	ep->datainterval = fmt->datainterval;
+	ep->maxpacksize = fmt->maxpacksize;
+	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
+
+	if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_FULL)
+		ep->freqn = get_usb_full_speed_rate(params_rate(hw_params));
+	else
+		ep->freqn = get_usb_high_speed_rate(params_rate(hw_params));
+
+	/* calculate the frequency in 16.16 format */
+	ep->freqm = ep->freqn;
+	ep->freqshift = INT_MIN;
+
+	ep->phase = 0;
+
+	switch (ep->type) {
+	case  SND_USB_ENDPOINT_TYPE_DATA:
+		err = data_ep_set_params(ep, hw_params, fmt, sync_ep);
+		break;
+	case  SND_USB_ENDPOINT_TYPE_SYNC:
+		err = sync_ep_set_params(ep, hw_params, fmt);
+		break;
+	default:
+		err = -EINVAL;
+	}
+
+	snd_printdd(KERN_DEBUG "Setting params for ep #%x (type %d, %d urbs), ret=%d\n",
+		   ep->ep_num, ep->type, ep->nurbs, err);
+
+	return err;
 }
 
-/*
- * process after capture sync complete
- * - nothing to do
+/**
+ * snd_usb_endpoint_start: start an snd_usb_endpoint
+ *
+ * @ep: the endpoint to start
+ *
+ * A call to this function will increment the use count of the endpoint.
+ * In case it is not already running, the URBs for this endpoint will be
+ * submitted. Otherwise, this function does nothing.
+ *
+ * Must be balanced to calls of snd_usb_endpoint_stop().
+ *
+ * Returns an error if the URB submission failed, 0 in all other cases.
  */
-static int retire_capture_sync_urb(struct snd_usb_substream *subs,
-				   struct snd_pcm_runtime *runtime,
-				   struct urb *urb)
+int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
 {
+	int err;
+	unsigned int i;
+
+	if (ep->chip->shutdown)
+		return -EBADFD;
+
+	/* already running? */
+	if (++ep->use_count != 1)
+		return 0;
+
+	if (snd_BUG_ON(!test_bit(EP_FLAG_ACTIVATED, &ep->flags)))
+		return -EINVAL;
+
+	/* just to be sure */
+	deactivate_urbs(ep, 0, 1);
+	wait_clear_urbs(ep);
+
+	ep->active_mask = 0;
+	ep->unlink_mask = 0;
+	ep->phase = 0;
+
+	/*
+	 * If this endpoint has a data endpoint as implicit feedback source,
+	 * don't start the urbs here. Instead, mark them all as available,
+	 * wait for the record urbs to return and queue the playback urbs
+	 * from that context.
+	 */
+
+	set_bit(EP_FLAG_RUNNING, &ep->flags);
+
+	if (snd_usb_endpoint_implict_feedback_sink(ep)) {
+		for (i = 0; i < ep->nurbs; i++) {
+			struct snd_urb_ctx *ctx = ep->urb + i;
+			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
+		}
+
+		return 0;
+	}
+
+	for (i = 0; i < ep->nurbs; i++) {
+		struct urb *urb = ep->urb[i].urb;
+
+		if (snd_BUG_ON(!urb))
+			goto __error;
+
+		if (usb_pipeout(ep->pipe)) {
+			prepare_outbound_urb_sizes(ep, urb->context);
+			prepare_outbound_urb(ep, urb->context);
+		} else {
+			prepare_inbound_urb(ep, urb->context);
+		}
+
+		err = usb_submit_urb(urb, GFP_ATOMIC);
+		if (err < 0) {
+			snd_printk(KERN_ERR "cannot submit urb %d, error %d: %s\n",
+				   i, err, usb_error_string(err));
+			goto __error;
+		}
+		set_bit(i, &ep->active_mask);
+	}
+
 	return 0;
+
+__error:
+	clear_bit(EP_FLAG_RUNNING, &ep->flags);
+	ep->use_count--;
+	deactivate_urbs(ep, 0, 0);
+	return -EPIPE;
 }
 
-/*
- * prepare urb for capture data pipe
+/**
+ * snd_usb_endpoint_stop: stop an snd_usb_endpoint
+ *
+ * @ep: the endpoint to stop (may be NULL)
  *
- * fill the offset and length of each descriptor.
+ * A call to this function will decrement the use count of the endpoint.
+ * In case the last user has requested the endpoint stop, the URBs will
+ * actually be deactivated.
  *
- * we use a temporary buffer to write the captured data.
- * since the length of written data is determined by host, we cannot
- * write onto the pcm buffer directly...  the data is thus copied
- * later at complete callback to the global buffer.
+ * Must be balanced to calls of snd_usb_endpoint_start().
  */
-static int prepare_capture_urb(struct snd_usb_substream *subs,
-			       struct snd_pcm_runtime *runtime,
-			       struct urb *urb)
+void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep,
+			   int force, int can_sleep, int wait)
 {
-	int i, offs;
-	struct snd_urb_ctx *ctx = urb->context;
+	if (!ep)
+		return;
 
-	offs = 0;
-	urb->dev = ctx->subs->dev; /* we need to set this at each time */
-	for (i = 0; i < ctx->packets; i++) {
-		urb->iso_frame_desc[i].offset = offs;
-		urb->iso_frame_desc[i].length = subs->curpacksize;
-		offs += subs->curpacksize;
+	if (snd_BUG_ON(ep->use_count == 0))
+		return;
+
+	if (snd_BUG_ON(!test_bit(EP_FLAG_ACTIVATED, &ep->flags)))
+		return;
+
+	if (--ep->use_count == 0) {
+		deactivate_urbs(ep, force, can_sleep);
+		ep->data_subs = NULL;
+		ep->sync_slave = NULL;
+		ep->retire_data_urb = NULL;
+		ep->prepare_data_urb = NULL;
+
+		if (wait)
+			wait_clear_urbs(ep);
 	}
-	urb->transfer_buffer_length = offs;
-	urb->number_of_packets = ctx->packets;
-	return 0;
 }
 
-/*
- * process after capture complete
+/**
+ * snd_usb_endpoint_activate: activate an snd_usb_endpoint
+ *
+ * @ep: the endpoint to activate
+ *
+ * If the endpoint is not currently in use, this functions will select the
+ * correct alternate interface setting for the interface of this endpoint.
  *
- * copy the data from each desctiptor to the pcm buffer, and
- * update the current position.
+ * In case of any active users, this functions does nothing.
+ *
+ * Returns an error if usb_set_interface() failed, 0 in all other
+ * cases.
  */
-static int retire_capture_urb(struct snd_usb_substream *subs,
-			      struct snd_pcm_runtime *runtime,
-			      struct urb *urb)
+int snd_usb_endpoint_activate(struct snd_usb_endpoint *ep)
 {
-	unsigned long flags;
-	unsigned char *cp;
-	int i;
-	unsigned int stride, frames, bytes, oldptr;
-	int period_elapsed = 0;
+	if (ep->use_count != 0)
+		return 0;
 
-	stride = runtime->frame_bits >> 3;
+	if (!ep->chip->shutdown &&
+	    !test_and_set_bit(EP_FLAG_ACTIVATED, &ep->flags)) {
+		int ret;
 
-	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("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);
+		ret = usb_set_interface(ep->chip->dev, ep->iface, ep->alt_idx);
+		if (ret < 0) {
+			snd_printk(KERN_ERR "%s() usb_set_interface() failed, ret = %d\n",
+						__func__, ret);
+			clear_bit(EP_FLAG_ACTIVATED, &ep->flags);
+			return ret;
 		}
+
+		return 0;
 	}
-	if (period_elapsed)
-		snd_pcm_period_elapsed(subs->pcm_substream);
-	return 0;
+
+	return -EBUSY;
 }
 
-/*
- * Process after capture complete when paused.  Nothing to do.
+/**
+ * snd_usb_endpoint_deactivate: deactivate an snd_usb_endpoint
+ *
+ * @ep: the endpoint to deactivate
+ *
+ * If the endpoint is not currently in use, this functions will select the
+ * alternate interface setting 0 for the interface of this endpoint.
+ *
+ * In case of any active users, this functions does nothing.
+ *
+ * Returns an error if usb_set_interface() failed, 0 in all other
+ * cases.
  */
-static int retire_paused_capture_urb(struct snd_usb_substream *subs,
-				     struct snd_pcm_runtime *runtime,
-				     struct urb *urb)
+int snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep)
 {
-	return 0;
-}
+	if (!ep)
+		return -EINVAL;
 
+	if (ep->use_count != 0)
+		return 0;
 
-/*
- * prepare urb for playback sync pipe
+	if (!ep->chip->shutdown &&
+	    test_and_clear_bit(EP_FLAG_ACTIVATED, &ep->flags)) {
+		int ret;
+
+		ret = usb_set_interface(ep->chip->dev, ep->iface, 0);
+		if (ret < 0) {
+			snd_printk(KERN_ERR "%s(): usb_set_interface() failed, ret = %d\n",
+						__func__, ret);
+			return ret;
+		}
+
+		return 0;
+	}
+
+	return -EBUSY;
+}
+
+/**
+ * snd_usb_endpoint_free: Free the resources of an snd_usb_endpoint
+ *
+ * @ep: the list header of the endpoint to free
  *
- * set up the offset and length to receive the current frequency.
+ * This function does not care for the endpoint's use count but will tear
+ * down all the streaming URBs immediately and free all resources.
  */
-static int prepare_playback_sync_urb(struct snd_usb_substream *subs,
-				     struct snd_pcm_runtime *runtime,
-				     struct urb *urb)
+void snd_usb_endpoint_free(struct list_head *head)
 {
-	struct snd_urb_ctx *ctx = urb->context;
+	struct snd_usb_endpoint *ep;
 
-	urb->dev = ctx->subs->dev; /* we need to set this at each time */
-	urb->iso_frame_desc[0].length = min(4u, ctx->subs->syncmaxsize);
-	urb->iso_frame_desc[0].offset = 0;
-	return 0;
+	ep = list_entry(head, struct snd_usb_endpoint, list);
+	release_urbs(ep, 1);
+	kfree(ep);
 }
 
-/*
- * process after playback sync complete
- *
- * Full speed devices report feedback values in 10.14 format as samples per
- * frame, high speed devices in 16.16 format as samples per microframe.
- * Because the Audio Class 1 spec was written before USB 2.0, many high speed
- * devices use a wrong interpretation, some others use an entirely different
- * format.  Therefore, we cannot predict what format any particular device uses
- * and must detect it automatically.
+/**
+ * snd_usb_handle_sync_urb: parse an USB sync packet
+ *
+ * @ep: the endpoint to handle the packet
+ * @sender: the sending endpoint
+ * @urb: the received packet
+ *
+ * This function is called from the context of an endpoint that received
+ * the packet and is used to let another endpoint object handle the payload.
  */
-static int retire_playback_sync_urb(struct snd_usb_substream *subs,
-				    struct snd_pcm_runtime *runtime,
-				    struct urb *urb)
+void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
+			     struct snd_usb_endpoint *sender,
+			     const struct urb *urb)
 {
-	unsigned int f;
 	int shift;
+	unsigned int f;
 	unsigned long flags;
 
+	snd_BUG_ON(ep == sender);
+
+	/*
+	 * In case the endpoint is operating in implicit feedback mode, prepare
+	 * a new outbound URB that has the same layout as the received packet
+	 * and add it to the list of pending urbs. queue_pending_output_urbs()
+	 * will take care of them later.
+	 */
+	if (snd_usb_endpoint_implict_feedback_sink(ep) &&
+	    ep->use_count != 0) {
+
+		/* implicit feedback case */
+		int i, bytes = 0;
+		struct snd_urb_ctx *in_ctx;
+		struct snd_usb_packet_info *out_packet;
+
+		in_ctx = urb->context;
+
+		/* Count overall packet size */
+		for (i = 0; i < in_ctx->packets; i++)
+			if (urb->iso_frame_desc[i].status == 0)
+				bytes += urb->iso_frame_desc[i].actual_length;
+
+		/*
+		 * skip empty packets. At least M-Audio's Fast Track Ultra stops
+		 * streaming once it received a 0-byte OUT URB
+		 */
+		if (bytes == 0)
+			return;
+
+		spin_lock_irqsave(&ep->lock, flags);
+		out_packet = ep->next_packet + ep->next_packet_write_pos;
+
+		/*
+		 * Iterate through the inbound packet and prepare the lengths
+		 * for the output packet. The OUT packet we are about to send
+		 * will have the same amount of payload bytes than the IN
+		 * packet we just received.
+		 */
+
+		out_packet->packets = in_ctx->packets;
+		for (i = 0; i < in_ctx->packets; i++) {
+			if (urb->iso_frame_desc[i].status == 0)
+				out_packet->packet_size[i] =
+					urb->iso_frame_desc[i].actual_length / ep->stride;
+			else
+				out_packet->packet_size[i] = 0;
+		}
+
+		ep->next_packet_write_pos++;
+		ep->next_packet_write_pos %= MAX_URBS;
+		spin_unlock_irqrestore(&ep->lock, flags);
+		queue_pending_output_urbs(ep);
+
+		return;
+	}
+
+	/*
+	 * process after playback sync complete
+	 *
+	 * Full speed devices report feedback values in 10.14 format as samples
+	 * per frame, high speed devices in 16.16 format as samples per
+	 * microframe.
+	 *
+	 * Because the Audio Class 1 spec was written before USB 2.0, many high
+	 * speed devices use a wrong interpretation, some others use an
+	 * entirely different format.
+	 *
+	 * Therefore, we cannot predict what format any particular device uses
+	 * and must detect it automatically.
+	 */
+
 	if (urb->iso_frame_desc[0].status != 0 ||
 	    urb->iso_frame_desc[0].actual_length < 3)
-		return 0;
+		return;
 
 	f = le32_to_cpup(urb->transfer_buffer);
 	if (urb->iso_frame_desc[0].actual_length == 3)
 		f &= 0x00ffffff;
 	else
 		f &= 0x0fffffff;
+
 	if (f == 0)
-		return 0;
+		return;
 
-	if (unlikely(subs->freqshift == INT_MIN)) {
+	if (unlikely(ep->freqshift == INT_MIN)) {
 		/*
 		 * The first time we see a feedback value, determine its format
 		 * by shifting it left or right until it matches the nominal
@@ -569,398 +1128,34 @@ static int retire_playback_sync_urb(struct snd_usb_substream *subs,
 		 * differ from the nominal value more than +50% or -25%.
 		 */
 		shift = 0;
-		while (f < subs->freqn - subs->freqn / 4) {
+		while (f < ep->freqn - ep->freqn / 4) {
 			f <<= 1;
 			shift++;
 		}
-		while (f > subs->freqn + subs->freqn / 2) {
+		while (f > ep->freqn + ep->freqn / 2) {
 			f >>= 1;
 			shift--;
 		}
-		subs->freqshift = shift;
-	}
-	else if (subs->freqshift >= 0)
-		f <<= subs->freqshift;
+		ep->freqshift = shift;
+	} else if (ep->freqshift >= 0)
+		f <<= ep->freqshift;
 	else
-		f >>= -subs->freqshift;
+		f >>= -ep->freqshift;
 
-	if (likely(f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax)) {
+	if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
 		/*
 		 * If the frequency looks valid, set it.
 		 * This value is referred to in prepare_playback_urb().
 		 */
-		spin_lock_irqsave(&subs->lock, flags);
-		subs->freqm = f;
-		spin_unlock_irqrestore(&subs->lock, flags);
+		spin_lock_irqsave(&ep->lock, flags);
+		ep->freqm = f;
+		spin_unlock_irqrestore(&ep->lock, flags);
 	} else {
 		/*
 		 * Out of range; maybe the shift value is wrong.
 		 * Reset it so that we autodetect again the next time.
 		 */
-		subs->freqshift = INT_MIN;
-	}
-
-	return 0;
-}
-
-/* determine the number of frames in the next packet */
-static int snd_usb_audio_next_packet_size(struct snd_usb_substream *subs)
-{
-	if (subs->fill_max)
-		return subs->maxframesize;
-	else {
-		subs->phase = (subs->phase & 0xffff)
-			+ (subs->freqm << subs->datainterval);
-		return min(subs->phase >> 16, subs->maxframesize);
+		ep->freqshift = INT_MIN;
 	}
 }
 
-/*
- * Prepare urb for streaming before playback starts or when paused.
- *
- * We don't have any data, so we send silence.
- */
-static int prepare_nodata_playback_urb(struct snd_usb_substream *subs,
-				       struct snd_pcm_runtime *runtime,
-				       struct urb *urb)
-{
-	unsigned int i, offs, counts;
-	struct snd_urb_ctx *ctx = urb->context;
-	int stride = runtime->frame_bits >> 3;
-
-	offs = 0;
-	urb->dev = ctx->subs->dev;
-	for (i = 0; i < ctx->packets; ++i) {
-		counts = snd_usb_audio_next_packet_size(subs);
-		urb->iso_frame_desc[i].offset = offs * stride;
-		urb->iso_frame_desc[i].length = counts * stride;
-		offs += counts;
-	}
-	urb->number_of_packets = ctx->packets;
-	urb->transfer_buffer_length = offs * stride;
-	memset(urb->transfer_buffer,
-	       runtime->format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0,
-	       offs * stride);
-	return 0;
-}
-
-/*
- * prepare urb for playback data pipe
- *
- * 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 int prepare_playback_urb(struct snd_usb_substream *subs,
-				struct snd_pcm_runtime *runtime,
-				struct urb *urb)
-{
-	int i, stride;
-	unsigned int counts, frames, bytes;
-	unsigned long flags;
-	int period_elapsed = 0;
-	struct snd_urb_ctx *ctx = urb->context;
-
-	stride = runtime->frame_bits >> 3;
-
-	frames = 0;
-	urb->dev = ctx->subs->dev; /* we need to set this at each time */
-	urb->number_of_packets = 0;
-	spin_lock_irqsave(&subs->lock, flags);
-	for (i = 0; i < ctx->packets; i++) {
-		counts = snd_usb_audio_next_packet_size(subs);
-		/* 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) /* 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;
-
-	/* 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);
-	return 0;
-}
-
-/*
- * process after playback data complete
- * - decrease the delay count again
- */
-static int retire_playback_urb(struct snd_usb_substream *subs,
-			       struct snd_pcm_runtime *runtime,
-			       struct urb *urb)
-{
-	unsigned long flags;
-	int stride = runtime->frame_bits >> 3;
-	int processed = urb->transfer_buffer_length / stride;
-	int est_delay;
-
-	spin_lock_irqsave(&subs->lock, flags);
-
-	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)
-		snd_printk(KERN_DEBUG "delay: estimated %d, actual %d\n",
-			est_delay, subs->last_delay);
-
-	spin_unlock_irqrestore(&subs->lock, flags);
-	return 0;
-}
-
-static const char *usb_error_string(int err)
-{
-	switch (err) {
-	case -ENODEV:
-		return "no device";
-	case -ENOENT:
-		return "endpoint not enabled";
-	case -EPIPE:
-		return "endpoint stalled";
-	case -ENOSPC:
-		return "not enough bandwidth";
-	case -ESHUTDOWN:
-		return "device disabled";
-	case -EHOSTUNREACH:
-		return "device suspended";
-	case -EINVAL:
-	case -EAGAIN:
-	case -EFBIG:
-	case -EMSGSIZE:
-		return "internal error";
-	default:
-		return "unknown error";
-	}
-}
-
-/*
- * set up and start data/sync urbs
- */
-static int start_urbs(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime)
-{
-	unsigned int i;
-	int err;
-
-	if (subs->stream->chip->shutdown)
-		return -EBADFD;
-
-	for (i = 0; i < subs->nurbs; i++) {
-		if (snd_BUG_ON(!subs->dataurb[i].urb))
-			return -EINVAL;
-		if (subs->ops.prepare(subs, runtime, subs->dataurb[i].urb) < 0) {
-			snd_printk(KERN_ERR "cannot prepare datapipe for urb %d\n", i);
-			goto __error;
-		}
-	}
-	if (subs->syncpipe) {
-		for (i = 0; i < SYNC_URBS; i++) {
-			if (snd_BUG_ON(!subs->syncurb[i].urb))
-				return -EINVAL;
-			if (subs->ops.prepare_sync(subs, runtime, subs->syncurb[i].urb) < 0) {
-				snd_printk(KERN_ERR "cannot prepare syncpipe for urb %d\n", i);
-				goto __error;
-			}
-		}
-	}
-
-	subs->active_mask = 0;
-	subs->unlink_mask = 0;
-	subs->running = 1;
-	for (i = 0; i < subs->nurbs; i++) {
-		err = usb_submit_urb(subs->dataurb[i].urb, GFP_ATOMIC);
-		if (err < 0) {
-			snd_printk(KERN_ERR "cannot submit datapipe "
-				   "for urb %d, error %d: %s\n",
-				   i, err, usb_error_string(err));
-			goto __error;
-		}
-		set_bit(i, &subs->active_mask);
-	}
-	if (subs->syncpipe) {
-		for (i = 0; i < SYNC_URBS; i++) {
-			err = usb_submit_urb(subs->syncurb[i].urb, GFP_ATOMIC);
-			if (err < 0) {
-				snd_printk(KERN_ERR "cannot submit syncpipe "
-					   "for urb %d, error %d: %s\n",
-					   i, err, usb_error_string(err));
-				goto __error;
-			}
-			set_bit(i + 16, &subs->active_mask);
-		}
-	}
-	return 0;
-
- __error:
-	// snd_pcm_stop(subs->pcm_substream, SNDRV_PCM_STATE_XRUN);
-	deactivate_urbs(subs, 0, 0);
-	return -EPIPE;
-}
-
-
-/*
- */
-static struct snd_urb_ops audio_urb_ops[2] = {
-	{
-		.prepare =	prepare_nodata_playback_urb,
-		.retire =	retire_playback_urb,
-		.prepare_sync =	prepare_playback_sync_urb,
-		.retire_sync =	retire_playback_sync_urb,
-	},
-	{
-		.prepare =	prepare_capture_urb,
-		.retire =	retire_capture_urb,
-		.prepare_sync =	prepare_capture_sync_urb,
-		.retire_sync =	retire_capture_sync_urb,
-	},
-};
-
-/*
- * initialize the substream instance.
- */
-
-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;
-	subs->ops = audio_urb_ops[stream];
-	if (snd_usb_get_speed(subs->dev) >= USB_SPEED_HIGH)
-		subs->ops.prepare_sync = prepare_capture_sync_urb_hs;
-
-	snd_usb_set_pcm_ops(as->pcm, stream);
-
-	list_add_tail(&fp->list, &subs->fmt_list);
-	subs->formats |= fp->formats;
-	subs->endpoint = fp->endpoint;
-	subs->num_formats++;
-	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(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(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)
-{
-	/* clear urbs (to be sure) */
-	deactivate_urbs(subs, 0, 1);
-	wait_clear_urbs(subs);
-
-	/* 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) {
-		subs->ops.prepare = prepare_nodata_playback_urb;
-		return start_urbs(subs, runtime);
-	}
-
-	return 0;
-}
-