Hi Sakamoto-san
The 'lock' is what I mentioned in former message to you:
[alsa-devel] Can I stop sound from driver as system error ? http://mailman.alsa-project.org/pipermail/alsa-devel/2015-December/102010.ht...
Yes, I had asked same question to ML, I'm sorry about that. And, can I confirm about your concern ? I guess you are worrying about dead-lock by stop xrun, but is that correct ?
Recent SoC tends to accumurate much IPs with variety functionalities.
If your SoC, R-Car, has such IPs and snd-soc-rcar utilize it, I can assume that snd-soc-rcar require to wait for some events after operating to the IPs. Or snd-soc-rcar require to manage race conditions between many PCM substreams.
In this case, current structure of snd-soc-rcar may cause problems (at least, in the end of last year), because it pushes many operations into 'struct snd_pcm_ops.trigger'. This callback is executed in both of process context and interrupt context and drivers should not wait for events or should not manage race conditions.
Thank you for explaining detail of your concern. I believe snd-soc-rcar is OK at this point, but of course not sure in the future. I will keep considering your advice, and fix any problems step-by-step. Thanks again