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ALSA: pcm: allow for trigger_tstamp snapshot in .trigger

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Don't use generic snapshot of trigger_tstamp if low-level driver or
hardware can get a more precise value for better audio/system time
synchronization.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Pierre-Louis Bossart 2015-02-06 15:55:51 -06:00 committed by Takashi Iwai
parent 0d59b81435
commit 2b79d7a6bf
2 changed files with 4 additions and 1 deletions
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1
include/sound/pcm.h
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@ -285,6 +285,7 @@ struct snd_pcm_runtime {
/* -- Status -- */
struct snd_pcm_substream *trigger_master;
struct timespec trigger_tstamp; /* trigger timestamp */
bool trigger_tstamp_latched; /* trigger timestamp latched in low-level driver/hardware */
int overrange;
snd_pcm_uframes_t avail_max;
snd_pcm_uframes_t hw_ptr_base; /* Position at buffer restart */

4
sound/core/pcm_native.c
View File

@ -810,7 +810,8 @@ static void snd_pcm_trigger_tstamp(struct snd_pcm_substream *substream)
if (runtime->trigger_master == NULL)
return;
if (runtime->trigger_master == substream) {
snd_pcm_gettime(runtime, &runtime->trigger_tstamp);
if (!runtime->trigger_tstamp_latched)
snd_pcm_gettime(runtime, &runtime->trigger_tstamp);
} else {
snd_pcm_trigger_tstamp(runtime->trigger_master);
runtime->trigger_tstamp = runtime->trigger_master->runtime->trigger_tstamp;
@ -979,6 +980,7 @@ static int snd_pcm_pre_start(struct snd_pcm_substream *substream, int state)
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
!snd_pcm_playback_data(substream))
return -EPIPE;
runtime->trigger_tstamp_latched = false;
runtime->trigger_master = substream;
return 0;
}