On Mon, 14 Nov 2022 15:08:17 +0100, Cezary Rojewski wrote: > > > > On 2022-11-14 2:02 PM, Takashi Iwai wrote: > > On Mon, 14 Nov 2022 12:37:29 +0100, > > Cezary Rojewski wrote: > >> > >> To improve performance and overall system stability, suspend/resume > >> operations for ASoC cards always return success status and defer the > >> actual work. > >> > >> Because of that, if a substream fails to resume, userspace may still > >> attempt to invoke commands on it as from their perspective the operation > >> completed successfully. Set substream's state to DISCONNECTED to ensure > >> no further commands are attempted. > > ... > > > Hm, that might work, but note that, once when the stream is set with > > the disconnected state, it won't be taken back to the normal state any > > longer on most sound backends. That is, it'll be gone and won't > > revive unless you completely unload and reload the whole stuff. If > > that's the intended behavior, that's fine, of course. So just to make > > sure. > > Good point. > > Our intention: if we fail e.g.: on resume, we would like the framework > to invoke ->hw_free() and close us. Right now, if we pretend that > everything is okay, invalid actions can be performed on our > streams. This all comes down to userspace calling "just" > snd_pcm_resume(). If we had an option to opt-in to a _hw_params() + > _prepare() + _resume() path, then things would look differently. So you'd rather like to make the stream appearing and working after re-opening the stream again? Then DISCONNECTED state might be too strong. If the broken state could be recovered by the PCM PREPARE phase, then we may (ab-)use XRUN state, instead. Then application shall re-setup via PCM prepare call. But if hw_free/hw_params is required, it won't work. Other than that, there is no such PCM state that forces to close and re-open, I'm afraid. You can have an internal error state and let the stream returning an error at each operation, instead, too. And, creating a new PCM state is very difficult. It would influence way too much, IMO, as each application code has to be modified to handle the new PCM state. Takashi
