When using switchable graphics in Lenovo Legion 5 15ARH05, the AMD Renoir APU
works along with NVIDIA Graphics(even non-free and prime works) but the
brightness cannot be controlled by the Fn keys, Software or
/sys/class/backlight

I've tried setting all the kernel params like acpi_backlight=vender or native
but the brightness control still does not work.

I highly suspect it's a bug in the amdgpu kernel driver. For now nvidia
graphics card works with brightness control.

It is also worthy to note that cat /sys/class/backlight/*/actual_brightness
always returns 311 and does not change even when executed echo 50 >
/sys/class/backlight/*/brightness

There are number of reports on this issue over the internet but nothing
official. I've tried a lot of linux distros and none of them work and it seems
it is broken even in the mainline kernel. I've also tried Kernel:HEAD version
of the kernel without the nvidia graphics support but still the brightness
control does not work. At the time writing I've booted linux 5.11-rc2 but the
brightness control still does not work.