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Commit ae1ec5e1 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: usbaudio - Add delay account 



Manage the PCM delay account based on the queued URBs.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 4bbe1ddf

sound/usb/usbaudio.c

+13 −1
Original line number Diff line number Diff line
@@ -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);