ALSA Compress API - system suspend/resume

[Pierre-Louis Bossart]

On 10/4/22 11:07 AM, Daniel Baluta wrote:
> Hello all,
> 
> It looks like system suspend is not implemented for Compress streams.
> 
> Any story behind this? Were there any attempts on implementing this?

It depends on the definition of 'system suspend'.

What we had in mind back in the early 2010s was to allow for 'active 
suspend' aka S0ix or low-power playback. That was the main reason for 
introducing the API.

For suspend to S3/D3, the plan was to just completely stop any 
playback/capture and restart on resume. I am not sure if this was ever 
implemented, that may be a miss.

There is a corner case we may have overlooked. I am not sure what 
happens if the S3/D3 suspend while playing. This is supported with e.g. 
aplay but for the compressed case it's a bit more complicated. Not all 
formats support rendering for a random position.