vc4.ko brings unusable&unstable ALSA sinks

[Ryutaroh Matsumoto]

Hi Diederik,

>> > bcm2835_audio bcm2835_audio: vchi message timeout
>> I think I've seen that msg too.
>> I don't know what my config was with that; tried so many.

I failed to include you in recipients of my message on Sun, 28 Mar 2021
( http://lists.infradead.org/pipermail/linux-rpi-kernel/2021-March/008078.html )
>>> 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?
>I think the root cause of this issue is that both vc4.ko and snd_bcm2835.ko
>try to provide ALSA sinks to HDMI audio outputs from RPi.

I strongly believe that module_blacklisting either vc4.ko or snd_bcm2835.ko
should fix your problem...

In theory, giving the module option "enable_hdmi=0" to snd_bcm2835.ko
should also fix the problem, but AFAIK snd_bcm2835.ko ignores the module
option "enable_hdmi=0".

Best regards, Ryutaroh