Sound issues with the 5.10.x kernel (alsa)

[Ryutaroh Matsumoto]

>> i assume you set this option in the config.txt? This shouldn't have any
>> affect for the mainline kernel / DT.
> I am aware of that...

I include my config.txt on RPi4B for reference...
arm_64bit=1
enable_uart=1
upstream_kernel=1
kernel=vmlinuz-5.10.0-5-rt-arm64
initramfs initrd.img-5.10.0-5-rt-arm64
disable_fw_kms_setup=1
disable_overscan=1
hdmi_enable_4kp60=1

Best regards, Ryutaroh Matsumoto