ALSA: usbaudio - Add delay account
Manage the PCM delay account based on the queued URBs.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 823296d..6c25fa2 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -627,6 +627,7 @@
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 @@
/*
* 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 @@
subs->hwptr_done = 0;
subs->transfer_done = 0;
subs->phase = 0;
+ runtime->delay = 0;
/* clear urbs (to be sure) */
deactivate_urbs(subs, 0, 1);