[regression] Headphone output gets unproperly powered down - Mi Notebook Pro 2020 (ALC256) (fwd of b.k.o bug #215484; starting with 5.14.14)

[Thorsten Leemhuis]

Hi, this is your Linux kernel regression tracker speaking.

I'm forwarding a regression reported in bugzilla.kernel.org to the list,
to make sure all parties interested in this are aware of it. The
reporter is CCed. Not CCing the stable list in this case, as 5.14 is EOL
already.

https://bugzilla.kernel.org/show_bug.cgi?id=215484

> With headphones (or an auxiliary jack) plugged in, the audio output
> is fine when anything is playing, but when that's stopped a loud pop
> can be heard after some seconds and if the jack is connected to an
> external amplifier it gets really noisy. Everything gets back to
> normal whenever audio playback is resumed, although with another loud
> pop at the start.
> 
> This has been happening since kernel 5.14.14, whereas 5.14.13 is
> fine. I suspect it has to do with the ALC256 mute logic implemented
> in that version
> (https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/diff/sound/pci/hda/patch_realtek.c?id=v5.14.14&id2=v5.14.13)
> 
> OS: Fedora Linux 35 Kernel: 5.16.0-60 Vanilla Hardware: Xiaomi Mi
> Notebook Pro Enhanced 2020 (i7 10510U, ALC256)

Ciao, Thorsten

#regzbot introduced v5.14.13..v5.14.14
#regzbot link: https://bugzilla.kernel.org/show_bug.cgi?id=215484
#regzbot from: Emanuele Melzi <itsbytebites at tutanota.com>