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[ALSA] Use posix clock monotonic for PCM and timer timestamps

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We need an accurate and continuous (monotonic) time sources to do
accurate synchronization among more timing sources. This patch allows
to enable monotonic timestamps for ALSA PCM devices and enables monotonic
timestamps for ALSA timer devices.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela
2007-12-13 10:19:42 +01:00
parent 25543fa785
commit b751eef1fd
5 changed files with 52 additions and 11 deletions
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10
include/sound/pcm.h
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@@ -323,6 +323,7 @@ struct snd_pcm_runtime {
/* -- timer -- */
unsigned int timer_resolution; /* timer resolution */
int tstamp_type; /* timestamp type */
/* -- DMA -- */
unsigned char *dma_area; /* DMA area */
@@ -952,6 +953,15 @@ void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream);
void snd_pcm_timer_init(struct snd_pcm_substream *substream);
void snd_pcm_timer_done(struct snd_pcm_substream *substream);
static inline void snd_pcm_gettime(struct snd_pcm_runtime *runtime,
struct timespec *tv)
{
if (runtime->tstamp_type == SNDRV_PCM_TSTAMP_TYPE_MONOTONIC)
do_posix_clock_monotonic_gettime(tv);
else
getnstimeofday(tv);
}
/*
* Memory
*/