On Wed, 2018-03-14 at 23:04 +0100, Takashi Iwai wrote:
On Wed, 14 Mar 2018 21:44:40 +0100, 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
The idea looks good, though, a bit of nitpicking:
include/sound/pcm.h | 6 ++++++ sound/core/pcm_lib.c | 15 ++++++++++----- 2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/include/sound/pcm.h b/include/sound/pcm.h index e054c583d3b3..e4694684c524 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 */
- unsigned wait_time; /* time in ms for R/W to wait for avail
*/
I'd name wait_timeout, which is slightly clearer.
/* -- next substream -- */ struct snd_pcm_substream *next; /* -- linked substreams -- */ @@ -579,6 +580,11 @@ int snd_pcm_start(struct snd_pcm_substream *substream); int snd_pcm_stop(struct snd_pcm_substream *substream, snd_pcm_state_t status); int snd_pcm_drain_done(struct snd_pcm_substream *substream); int snd_pcm_stop_xrun(struct snd_pcm_substream *substream); +static inline void snd_pcm_wait_time(struct snd_pcm_substream *substream,
- unsigned wait_time)
+{
- substream->wait_time = wait_time;
+}
IMO, it's a simple one parameter, and no need wrapping with an inline function.
This was for drivers to set the parameter according to HW capabilities.
#ifdef CONFIG_PM int snd_pcm_suspend(struct snd_pcm_substream *substream); int snd_pcm_suspend_all(struct snd_pcm *pcm); diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index a83152e7d387..2ee76c70f55f 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1839,12 +1839,17 @@ 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 = msecs_to_jiffies(substream->wait_time);} 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);This can go bad when wait_time is shorter than the period time. Some validation is needed?
Yes, and we should also validate no irq mode somehow too, probably using buffer time.
Also, how is user-space supposed to set the new parameter?
It's not atm, as it was being set by the driver. Would probably mean an ABI change to PCM ops or a new ioctl ? The latter wont break the ABI and the default value would remain if the ioctl was not called.
Liam
thanks,
Takashi