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@xxxxxxxxxxxxxxx>
> ---
>
> 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 (;;) {
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