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authorTakashi Iwai <tiwai@suse.de>2008-10-13 03:08:53 +0200
committerTakashi Iwai <tiwai@suse.de>2009-05-05 14:47:21 +0200
commitae1ec5e1e97f67d41e641a73380129e5905e41cc (patch)
treed6366e64044c20570724decdf2d6d10f1e476c97 /sound/usb
parent4bbe1ddf89a5ba3ec30fe5980912d8bda3a3cbb2 (diff)
ALSA: usbaudio - Add delay account
Manage the PCM delay account based on the queued URBs. Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb')
-rw-r--r--sound/usb/usbaudio.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 823296d7d57..6c25fa23f70 100644
--- a/sound/usb/usbaudio.c
+++ b/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);