Sound issues with the 5.10.x kernel (alsa)

[Ryutaroh Matsumoto]

> 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.

The difference in Debian kernel 5.10.9 was that vc4.ko was disabled by
mistake. I guess that module_blacklist=vc4 in kernel command line
suppresses the symptom.
All other Debian kernel 5.10.x have vc4.ko enabled in arm64.

Best regards, Ryutaroh