[PATCH] ASoC: Intel: haswell: Power transition refactor

[Pierre-Louis Bossart]

>>> Pierre, your thoughts on this? This has already been confirmed working.
>>
>> I don't have any specific knowledge on Broadwell to comment. I also 
>> haven't had time to test this patch, I was expecting Ross to provide 
>> his Tested-by tag?
> 
> Hello,
> 
> Ross has provided his Tested-by tag already. Patch has been tested by 
> Intel & Google side both. Given problem's impact, this fix is considered 
> a critical one. I think we are good-to-go for quite a while now?
> 
> Czarek

I just tested speaker playback on Dell XPS13 and Samus Chromebook to 
double-check my UCM2 changes for SOF were indeed backwards compatible 
with the SST driver case. Well, my changes are fine but the kernel not 
so much.

With a 5.8-rc1 kernel w/ the SST driver, sounds played through 
pulseaudio are rendered too slowly with clicky artefacts. Using the alsa 
hw device works fine. In some cases, the sound rendered by PulseAudio 
become clear again after a while. Restarting the UI and testing degrades 
the audio again.

Reverting this patch - identified with git bisect - solves the issue on 
both devices, pulseaudio works fine again without any transient 
behavior. I spent 15mn monkey-testing and the audio quality was always 
good when this patch is reverted.

I have no idea what the fixes were, but going from a somewhat random D3 
exit problem to a 100% reproducible issue is problematic. I trust both 
Cezary and Ross did test this patch, but could it be that pulseaudio 
tests were skipped?

8ec7d6043263ecf250b9b7c0dd8ade899487538a is the first bad commit
commit 8ec7d6043263ecf250b9b7c0dd8ade899487538a
Author: Cezary Rojewski <cezary.rojewski at intel.com>
Date:   Mon Mar 30 21:45:20 2020 +0200

     ASoC: Intel: haswell: Power transition refactor