AMD Ryzen 4800H Renior iGPU backlight brightness control not working (Hybrid Graphics) (Lenovo Legion 5 15ARH05)
Brief summary of the problem:
Brightness control does not work with AMD Ryzen 4800H Renior iGPU when using switchable graphics (aka. Hybrid graphics). The value of /sys/class/backlight/amdgpu_bl0/actual_brightness is stuck at 311. Brightness control only works with discrete graphics card. Brightness control somewhat worked with Fedora Workstation 32 with Linux Kernel 5.6.6 but now with 5.10.4 brightness control does not work.
- CPU: AMD Ryzen 7 4800H with Radeon Graphics
- GPU: NVIDIA 1650 Ti Mobile Graphics
- System Memory: 8 GB
- Display(s): Only one (Laptop Screen)
- Type of Diplay Connection: eDP
- Distro name and Version: OpenSUSE Tumbleweed
- Kernel version: 5.10.4
- AMD package version: 19.1.0-3.3 (xf86-video-amdgpu)
How to reproduce the issue:
Enable Switchable Graphics from BIOS and restart. Now you should have AMD iGPU and NVIDIA dGPU enabled. By default the panel uses iGPU for everything and offloads large graphical apps to dGPU.
Now try to change the brightness with software, Fn keys and changing /sys/class/backlight/amdgpu_bl0/brightness and the brightness will not change, i.e The brightness control will not respond and the brightness will always be at max.
It is worthy to note that the value of /sys/class/backlight/amdgpu_bl0/actual_brightness is stuck at 311 and does not change at all.
When using only the discrete graphics card the brightness control works perfectly.