On 2018/7/6 下午8:50, Liam Girdwood wrote:

Currently ALSA core blocks userspace for about 10 seconds for PCM R/W IO. This needs to be configurable for modern hardware like DSPs where no pointer update in milliseconds can indicate terminal DSP errors.

Add a substream variable to set the wait time in ms. This allows userspace and drivers to recover more quickly from terminal DSP errors.

Signed-off-by: Liam Girdwood liam.r.girdwood@linux.intel.com

Changes since V1 :- o Remove API method and alow drivers to set directly. o Validate time is driver supplied times.

V2 :- o Max wait calc now in ms. o checkpatch.

v3:- o Remove driver supplied time validation.

include/sound/pcm.h | 1 + sound/core/pcm_lib.c | 17 ++++++++++++----- 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/include/sound/pcm.h b/include/sound/pcm.h index e054c583d3b3..fcdf358a25f0 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -462,6 +462,7 @@ struct snd_pcm_substream { /* -- timer section -- */ struct snd_timer *timer; /* timer */ unsigned timer_running: 1; /* time is running */

• long wait_time; /* time in ms for R/W to wait for avail */ /* -- next substream -- */ struct snd_pcm_substream *next; /* -- linked substreams -- */

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 44b5ae833082..eecbfdc7a2c9 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1832,12 +1832,19 @@ static int wait_for_avail(struct snd_pcm_substream *substream, if (runtime->no_period_wakeup) wait_time = MAX_SCHEDULE_TIMEOUT; else {

• wait_time = 10;
  

• if (runtime->rate) {
  

• 	long t = runtime->period_size * 2 / runtime->rate;
  

• 	wait_time = max(t, wait_time);
  

• /* use wait time from substream if available */
  

• if (substream->wait_time) {
  

• 	wait_time = substream->wait_time;
  

I investigated the sof driver recently,  and found this  patch is a little bit confused,  if substream->wait_time is set, why don't  convert the wait_time to jiffies here? Is it a bug or an on-purpose design?

Thanks,

Hui.

• } else {
  

• 	wait_time = 10;
  

• 	if (runtime->rate) {
  

• 		long t = runtime->period_size * 2 /
  

• 			 runtime->rate;
  

• 		wait_time = max(t, wait_time);
  

• 	}
  

• 	wait_time = msecs_to_jiffies(wait_time * 1000);
  

  }

• wait_time = msecs_to_jiffies(wait_time * 1000);
  

  }

  for (;;) {