4 files changed, 72 insertions, 29 deletions

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 c41181202688..d6e2bb49c59c 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -141,7 +141,7 @@ 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;
@@ -177,15 +177,6 @@ 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.
  */
@@ -370,7 +361,6 @@ 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);
@@ -799,7 +789,9 @@ 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
@@ -809,7 +801,7 @@ 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;
@@ -821,6 +813,11 @@ 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;
@@ -850,7 +847,6 @@ 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;