[alsa-devel] [PATCH v5 02/10] ALSA: core: allow for trigger_tstamp snapshot in .trigger

[Takashi Iwai]

At Fri,  6 Feb 2015 15:55:51 -0600,
Pierre-Louis Bossart wrote:
> 
> 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 at linux.intel.com>

Applied, thanks.


Takashi


> ---
>  include/sound/pcm.h     | 1 +
>  sound/core/pcm_native.c | 4 +++-
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/include/sound/pcm.h b/include/sound/pcm.h
> index cd09c1b..e158036 100644
> --- a/include/sound/pcm.h
> +++ b/include/sound/pcm.h
> @@ -279,6 +279,7 @@ 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 */
> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> index 7bbc34d..d50f3e6 100644
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -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;
>  }
> -- 
> 1.9.1
> 
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