Sound issues with the 5.10.x kernel (alsa)

[Stefan Wahren]

Hi Diederik,

Am 08.02.21 um 12:47 schrieb Diederik de Haas:
> Hi,
>
> This is basically me forwarding the bug I reported on Debian's BTS:
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=978025
>
> TL;DR: I have a RPi 3B+ running pure Debian Bullseye arm64 (~from 
> raspi.debian.net), named rpi-mpd, connected via HDMI cable to my AV Receiver.
can you please confirm that the bcm2835-audio driver causing the issues?
> Playing music worked fine with kernel 5.9, but with 5.10.2-1 the music 
> (quality) became not good to quite horribly, because of (static) noise and 
> distortion.
> With kernel version 5.10.9 (linux-image-5.10.0-2-arm64) it all seemed fixed, 
> but returned with 5.10.12 (linux-image-5.10.0-3-arm64) and is also present 
> with 5.10.13.

I cannot explain why 5.10.9 works for you, but we had multiple
regressions in 5.10. Currently i cannot see any of the fixes by Phil
Elwell in linux-stable. Maybe they won't apply and needs to be backport
manually.

Just for reference here are the revelant patches:

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/staging/vc04_services?h=next-20210205&id=96ae327678eceabf455b11a88ba14ad540d4b046

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/staging/vc04_services?h=next-20210205&id=88753cc19f087abe0d39644b844e67a59cfb5a3d

Could you please try?

Best regards
Stefan

>
> I can consistently reproduce this issue, rebooting into 5.10.9 and playing 
> music is fine again, so I *think* this is not a local issue.
> This ML is the closest I can think of as 'upstream', so hopefully more insight  
> can be accomplished here ... and a fix.
>
> Cheers,
>   Diederik
>
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