At Mon, 20 Aug 2012 17:34:26 +0000, Sarawadi, Ravishankar wrote:
Greetings,
I recently started working with ALSA architecture. I am very excited to be part of ALSA group and this is my first query as ALSA developer.
This is in regards to function wait_for_avail() defined in pcm_lib.c If audio path is broken the wait_time inside this function is 10 seconds. wait_time = msecs_to_jiffies(wait_time * 1000);
I have a use case where I need to force exit out of this wait when audio hardware path is broken. Waiting for 10 seconds is too long and causing synchronization issues.
My Use-case:
1 PCM Audio playback is going on. PCM write is a blocking call. Waiting on DSP WRITE-DONE event.
2 Audio hardware path failure
3 PCM driver notified of hardware path failure.
4 Meanwhile DSP ring buffer gets full as buffers are not getting consumed.
5 Next WRITE is blocked on wait_for_avail() buffer call.
6 PCM close from driver as part process to handle audio path failure is blocked on Step 5
I am trying to figure out a way to exit out of this wait forcefully by some external trigger. Another option is to reduce this wait time to less than 5 seconds.
Could someone please recommend the best way to handle this use case?
The driver can wake up the sleeper at any time. For example, call snd_pcm_stop() with SNDRV_PCM_STATE_XRUN.
Takashi