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ALSA: usbaudio - Add delay account 

Manage the PCM delay account based on the queued URBs.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2008-10-13 03:08:53 +02:00
parent 4bbe1ddf89
commit ae1ec5e1e9
1 changed files with 13 additions and 1 deletions
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14
sound/usb/usbaudio.c
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@ -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);