Re: Regression apparently caused by commit 088a40980efbc2c449b72f0f2c7ebd82f71d08e2 "ASoC: amd: acp: add pm ops support for acp pci driver"

[Bagas Sanjaya]

On Thu, Aug 03, 2023 at 10:22:07PM +0300, Marian Postevca wrote:
> I'm trying to develop a sound machine driver based on the acp legacy driver.
> The first version of the driver was sent for review on the alsa mailing list this
> spring: https://lore.kernel.org/all/20230320203519.20137-1-posteuca@xxxxxxxxx
> 
> I'm trying to fix some of the issues that were brought up during the review back then,
> but when I ported the patches to the latest commit on the for-next
> branch, I noticed a regression where I couldn't hear any sound at all.
> 
> So I started a bisect session and found that the first bad commit is:
> ASoC: amd: acp: add pm ops support for acp pci driver
> commit 088a40980efbc2c449b72f0f2c7ebd82f71d08e2
> https://lore.kernel.org/lkml/20230622152406.3709231-11-Syed.SabaKareem@xxxxxxx
> 
> If I revert this commit sound works as expected. So I started tinkering a little bit
> with it and I believe that what happens is that the acp pci driver
> enters the autosuspend state and never leaves this state at all.
> I noticed this because if I increase the autosuspend delay to a much
> larger value, then the sound works until that delay passes.
> I added traces and I can see that when the delay expires the suspend callback snd_acp_suspend()
> gets called, but the resume callback snd_acp_resume() never gets called.
> 
> I'm no expert in runtime power management (though I did read a bit on it), so I don't understand
> all the things that happen underneath, but one thing that is not clear to me is who's supposed
> to mark activity on this device and keep it from entering autosuspend if the user wants to play
> some sound? Shouldn't there be some counterpart that calls pm_runtime_mark_last_busy() ?
> I looked through the code and can't find who's calling pm_runtime_mark_last_busy().
> 
> Some help here would be welcome. Is there something missing in my machine driver code, or
> is the runtime pm handling in acp pci driver wrong?

Thanks for the regression report. I'm adding it to regzbot:

#regzbot ^introduced: 088a40980efbc2

-- 
An old man doll... just what I always wanted! - Clara

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