From b751eef1fdffca5532344285f2fad0c60d2f0158 Mon Sep 17 00:00:00 2001 From: Jaroslav Kysela Date: Thu, 13 Dec 2007 10:19:42 +0100 Subject: [ALSA] Use posix clock monotonic for PCM and timer timestamps 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 --- sound/core/timer.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'sound/core/timer.c') diff --git a/sound/core/timer.c b/sound/core/timer.c index e7dc56c..7e5fe2d 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -44,11 +44,14 @@ #endif static int timer_limit = DEFAULT_TIMER_LIMIT; +static int timer_tstamp_monotonic = 1; MODULE_AUTHOR("Jaroslav Kysela , Takashi Iwai "); MODULE_DESCRIPTION("ALSA timer interface"); MODULE_LICENSE("GPL"); module_param(timer_limit, int, 0444); MODULE_PARM_DESC(timer_limit, "Maximum global timers in system."); +module_param(timer_tstamp_monotonic, int, 0444); +MODULE_PARM_DESC(timer_tstamp_monotonic, "Use posix monotonic clock source for timestamps (default)."); struct snd_timer_user { struct snd_timer_instance *timeri; @@ -381,7 +384,10 @@ static void snd_timer_notify1(struct snd_timer_instance *ti, int event) struct snd_timer_instance *ts; struct timespec tstamp; - getnstimeofday(&tstamp); + if (timer_tstamp_monotonic) + do_posix_clock_monotonic_gettime(&tstamp); + else + getnstimeofday(&tstamp); snd_assert(event >= SNDRV_TIMER_EVENT_START && event <= SNDRV_TIMER_EVENT_PAUSE, return); if (event == SNDRV_TIMER_EVENT_START || @@ -1182,8 +1188,12 @@ static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri, spin_unlock(&tu->qlock); return; } - if (tu->last_resolution != resolution || ticks > 0) - getnstimeofday(&tstamp); + if (tu->last_resolution != resolution || ticks > 0) { + if (timer_tstamp_monotonic) + do_posix_clock_monotonic_gettime(&tstamp); + else + getnstimeofday(&tstamp); + } if ((tu->filter & (1 << SNDRV_TIMER_EVENT_RESOLUTION)) && tu->last_resolution != resolution) { r1.event = SNDRV_TIMER_EVENT_RESOLUTION; -- cgit v1.1