diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index ec2118d0e27a..eb60cb8dbb8a 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -80,14 +80,12 @@ static int snd_compr_open(struct inode *inode, struct file *f)
 	int maj = imajor(inode);
 	int ret;
 
-	if (f->f_flags & O_WRONLY)
+	if ((f->f_flags & O_ACCMODE) == O_WRONLY)
 		dirn = SND_COMPRESS_PLAYBACK;
-	else if (f->f_flags & O_RDONLY)
+	else if ((f->f_flags & O_ACCMODE) == O_RDONLY)
 		dirn = SND_COMPRESS_CAPTURE;
-	else {
-		pr_err("invalid direction\n");
+	else
 		return -EINVAL;
-	}
 
 	if (maj == snd_major)
 		compr = snd_lookup_minor_data(iminor(inode),
diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index ff97cf3e8bad..d71d101e9293 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -2368,6 +2368,7 @@ int snd_hda_codec_reset(struct hda_codec *codec)
 	}
 	if (codec->patch_ops.free)
 		codec->patch_ops.free(codec);
+	memset(&codec->patch_ops, 0, sizeof(codec->patch_ops));
 	snd_hda_jack_tbl_clear(codec);
 	codec->proc_widget_hook = NULL;
 	codec->spec = NULL;
@@ -2383,7 +2384,6 @@ int snd_hda_codec_reset(struct hda_codec *codec)
 	codec->num_pcms = 0;
 	codec->pcm_info = NULL;
 	codec->preset = NULL;
-	memset(&codec->patch_ops, 0, sizeof(codec->patch_ops));
 	codec->slave_dig_outs = NULL;
 	codec->spdif_status_reset = 0;
 	module_put(codec->owner);
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 76ec2421fae1..e1a12c754de9 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -2796,6 +2796,7 @@ static struct snd_pci_quirk position_fix_list[] __devinitdata = {
 	SND_PCI_QUIRK(0x1043, 0x813d, "ASUS P5AD2", POS_FIX_LPIB),
 	SND_PCI_QUIRK(0x1043, 0x81b3, "ASUS", POS_FIX_LPIB),
 	SND_PCI_QUIRK(0x1043, 0x81e7, "ASUS M2V", POS_FIX_LPIB),
+	SND_PCI_QUIRK(0x1043, 0x1b43, "ASUS K53E", POS_FIX_POSBUF),
 	SND_PCI_QUIRK(0x104d, 0x9069, "Sony VPCS11V9E", POS_FIX_LPIB),
 	SND_PCI_QUIRK(0x10de, 0xcb89, "Macbook Pro 7,1", POS_FIX_LPIB),
 	SND_PCI_QUIRK(0x1297, 0x3166, "Shuttle", POS_FIX_LPIB),
diff --git a/sound/pci/hda/patch_sigmatel.c b/sound/pci/hda/patch_sigmatel.c
index c16d0f822b5b..eef9c6cad25d 100644
--- a/sound/pci/hda/patch_sigmatel.c
+++ b/sound/pci/hda/patch_sigmatel.c
@@ -1075,7 +1075,7 @@ static struct snd_kcontrol_new stac_smux_mixer = {
 
 static const char * const slave_pfxs[] = {
 	"Front", "Surround", "Center", "LFE", "Side",
-	"Headphone", "Speaker", "IEC958",
+	"Headphone", "Speaker", "IEC958", "PCM",
 	NULL
 };
 
diff --git a/sound/usb/card.c b/sound/usb/card.c
index d5b5c3388e28..4a469f0cb6d4 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -553,7 +553,7 @@ static void snd_usb_audio_disconnect(struct usb_device *dev,
 				     struct snd_usb_audio *chip)
 {
 	struct snd_card *card;
-	struct list_head *p;
+	struct list_head *p, *n;
 
 	if (chip == (void *)-1L)
 		return;
@@ -570,7 +570,7 @@ static void snd_usb_audio_disconnect(struct usb_device *dev,
 			snd_usb_stream_disconnect(p);
 		}
 		/* release the endpoint resources */
-		list_for_each(p, &chip->ep_list) {
+		list_for_each_safe(p, n, &chip->ep_list) {
 			snd_usb_endpoint_free(p);
 		}
 		/* release the midi resources */
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 94b08a6087a3..a83a18dbac25 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -142,7 +142,7 @@ int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep)
  *
  * For implicit feedback, next_packet_size() is unused.
  */
-static int next_packet_size(struct snd_usb_endpoint *ep)
+int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep)
 {
 	unsigned long flags;
 	int ret;
@@ -183,15 +183,6 @@ static void retire_inbound_urb(struct snd_usb_endpoint *ep,
 		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.
  */
@@ -376,7 +367,6 @@ static void snd_complete_urb(struct urb *urb)
 			goto exit_clear;
 		}
 
-		prepare_outbound_urb_sizes(ep, ctx);
 		prepare_outbound_urb(ep, ctx);
 	} else {
 		retire_inbound_urb(ep, ctx);
@@ -805,7 +795,9 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
 /**
  * snd_usb_endpoint_start: start an snd_usb_endpoint
  *
- * @ep: the endpoint to start
+ * @ep:		the endpoint to start
+ * @can_sleep:	flag indicating whether the operation is executed in
+ * 		non-atomic context
  *
  * 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
@@ -815,7 +807,7 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
  *
  * Returns an error if the URB submission failed, 0 in all other cases.
  */
-int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
+int snd_usb_endpoint_start(struct snd_usb_endpoint *ep, int can_sleep)
 {
 	int err;
 	unsigned int i;
@@ -827,6 +819,11 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
 	if (++ep->use_count != 1)
 		return 0;
 
+	/* just to be sure */
+	deactivate_urbs(ep, 0, can_sleep);
+	if (can_sleep)
+		wait_clear_urbs(ep);
+
 	ep->active_mask = 0;
 	ep->unlink_mask = 0;
 	ep->phase = 0;
@@ -858,7 +855,6 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
 			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);
diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h
index ee2723fb174f..cbbbdf226d66 100644
--- a/sound/usb/endpoint.h
+++ b/sound/usb/endpoint.h
@@ -13,7 +13,7 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
 				struct audioformat *fmt,
 				struct snd_usb_endpoint *sync_ep);
 
-int  snd_usb_endpoint_start(struct snd_usb_endpoint *ep);
+int  snd_usb_endpoint_start(struct snd_usb_endpoint *ep, int can_sleep);
 void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep,
 			   int force, int can_sleep, int wait);
 int  snd_usb_endpoint_activate(struct snd_usb_endpoint *ep);
@@ -21,6 +21,7 @@ int  snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep);
 void snd_usb_endpoint_free(struct list_head *head);
 
 int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep);
+int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep);
 
 void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
 			     struct snd_usb_endpoint *sender,
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 62ec808ed792..f782ce19bf5a 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -212,7 +212,7 @@ int snd_usb_init_pitch(struct snd_usb_audio *chip, int iface,
 	}
 }
 
-static int start_endpoints(struct snd_usb_substream *subs)
+static int start_endpoints(struct snd_usb_substream *subs, int can_sleep)
 {
 	int err;
 
@@ -225,7 +225,7 @@ static int start_endpoints(struct snd_usb_substream *subs)
 		snd_printdd(KERN_DEBUG "Starting data EP @%p\n", ep);
 
 		ep->data_subs = subs;
-		err = snd_usb_endpoint_start(ep);
+		err = snd_usb_endpoint_start(ep, can_sleep);
 		if (err < 0) {
 			clear_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags);
 			return err;
@@ -236,10 +236,25 @@ static int start_endpoints(struct snd_usb_substream *subs)
 	    !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->alt_idx != subs->sync_endpoint->alt_idx) {
+			err = usb_set_interface(subs->dev,
+						subs->sync_endpoint->iface,
+						subs->sync_endpoint->alt_idx);
+			if (err < 0) {
+				snd_printk(KERN_ERR
+					   "%d:%d:%d: cannot set interface (%d)\n",
+					   subs->dev->devnum,
+					   subs->sync_endpoint->iface,
+					   subs->sync_endpoint->alt_idx, err);
+				return -EIO;
+			}
+		}
+
 		snd_printdd(KERN_DEBUG "Starting sync EP @%p\n", ep);
 
 		ep->sync_slave = subs->data_endpoint;
-		err = snd_usb_endpoint_start(ep);
+		err = snd_usb_endpoint_start(ep, can_sleep);
 		if (err < 0) {
 			clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags);
 			return err;
@@ -544,13 +559,10 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
 	subs->last_frame_number = 0;
 	runtime->delay = 0;
 
-	/* clear the pending deactivation on the target EPs */
-	deactivate_endpoints(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)
-		return start_endpoints(subs);
+		return start_endpoints(subs, 1);
 
 	return 0;
 }
@@ -1032,6 +1044,7 @@ 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;
@@ -1043,7 +1056,11 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
 	urb->number_of_packets = 0;
 	spin_lock_irqsave(&subs->lock, flags);
 	for (i = 0; i < ctx->packets; i++) {
-		counts = ctx->packet_size[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 * stride;
 		urb->iso_frame_desc[i].length = counts * stride;
@@ -1094,7 +1111,16 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
 	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)
@@ -1112,12 +1138,32 @@ static void retire_playback_urb(struct snd_usb_substream *subs,
 	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;
 	int stride = runtime->frame_bits >> 3;
 	int processed = urb->transfer_buffer_length / 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 (processed > runtime->delay)
-		runtime->delay = 0;
+	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
-		runtime->delay -= processed;
+		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);
 }
 
@@ -1175,7 +1221,7 @@ static int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream
 
 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
-		err = start_endpoints(subs);
+		err = start_endpoints(subs, 0);
 		if (err < 0)
 			return err;