Comment # 6 on bug 1180749 from Antony J.R

(In reply to Takashi Iwai from comment #5)
> Actually, which backlight drivers are being used there?  Is it only ACPI or
> native driver?
> 
> And do I understand correctly that, if you switch to Nvidia driver (both mod
> setting and rendering), the backlight control works via
> /sys/class/backlight, while the same doesn't work if switching to AMDGPU?

To be exact, hybrid graphics brightness control does not work. Yes using only
the discrete graphics card with nvidia non-free software enables me to control
the backlight. But when switched to hybrid graphics(switchable graphics) the
iGPU brightness control will not work.