Merge branch 'topic/pcm-delay' into for-linus

* topic/pcm-delay:
  ALSA: usbaudio - Add delay account
  ALSA: Add extra delay count in PCM

include/sound/pcm.h

@@ -270,6 +270,7 @@ struct snd_pcm_runtime {
 	snd_pcm_uframes_t hw_ptr_base;	/* Position at buffer restart */
 	snd_pcm_uframes_t hw_ptr_interrupt; /* Position at interrupt time */
 	unsigned long hw_ptr_jiffies;	/* Time when hw_ptr is updated */
+	snd_pcm_sframes_t delay;	/* extra delay; typically FIFO size */
 
 	/* -- HW params -- */
 	snd_pcm_access_t access;	/* access mode */

sound/core/pcm_native.c

@@ -587,14 +587,15 @@ int snd_pcm_status(struct snd_pcm_substream *substream,
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		status->avail = snd_pcm_playback_avail(runtime);
 		if (runtime->status->state == SNDRV_PCM_STATE_RUNNING ||
-		    runtime->status->state == SNDRV_PCM_STATE_DRAINING)
+		    runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
 			status->delay = runtime->buffer_size - status->avail;
-		else
+			status->delay += runtime->delay;
+		} else
 			status->delay = 0;
 	} else {
 		status->avail = snd_pcm_capture_avail(runtime);
 		if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)
-			status->delay = status->avail;
+			status->delay = status->avail + runtime->delay;
 		else
 			status->delay = 0;
 	}
@@ -2410,6 +2411,7 @@ static int snd_pcm_delay(struct snd_pcm_substream *substream,
 			n = snd_pcm_playback_hw_avail(runtime);
 		else
 			n = snd_pcm_capture_avail(runtime);
+		n += runtime->delay;
 		break;
 	case SNDRV_PCM_STATE_XRUN:
 		err = -EPIPE;

sound/usb/usbaudio.c

@@ -627,6 +627,7 @@ static int prepare_playback_urb(struct snd_usb_substream *subs,
 	subs->hwptr_done += offs;
 	if (subs->hwptr_done >= runtime->buffer_size)
 		subs->hwptr_done -= runtime->buffer_size;
+	runtime->delay += offs;
 	spin_unlock_irqrestore(&subs->lock, flags);
 	urb->transfer_buffer_length = offs * stride;
 	if (period_elapsed)
@@ -636,12 +637,22 @@ static int prepare_playback_urb(struct snd_usb_substream *subs,
 
 /*
  * process after playback data complete
- * - nothing to do
+ * - 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;
+
+	spin_lock_irqsave(&subs->lock, flags);
+	if (processed > runtime->delay)
+		runtime->delay = 0;
+	else
+		runtime->delay -= processed;
+	spin_unlock_irqrestore(&subs->lock, flags);
 	return 0;
 }
 
@@ -1520,6 +1531,7 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
 	subs->hwptr_done = 0;
 	subs->transfer_done = 0;
 	subs->phase = 0;
+	runtime->delay = 0;
 
 	/* clear urbs (to be sure) */
 	deactivate_urbs(subs, 0, 1);