Erratic Brightness and Backlight Behaviour on R5600H + Nvidia RX 3050Ti on HP Victus 15 & EndeavourOS

So, I installed Endeavour OS and had minimal if not zero backlight bug and I tried to self-diagnose the issue.

Here’s a description of the problem

  • Brightness control on the software side works as expected
  • But the F2/F3 keys (laptop brightness hotkeys) result in inverted behavior (ie 5% brightness looks much brighter than 95%)
  • Kernel parameter changes results in max brightness but introduces lag

I insist that the software side is changing as expected because /sys/class/backlight/amdgpu_bl1/brightness changes and there is a relative change in perceived brightness also.

Specs

  • Linux Kernel 6 (latest kernel)
  • Nvidia RTX 3050Ti + Nvidia Drivers
  • AMD Ryzen 5600H
  • HP Victus 15

So, I did some research and tried to fix this using kernel parameters and here are the results of the different combinations I have tried.

amdgpu.backlight=0 >  max brightness, but stuck at 100% also heavy UI lag 

acpi_backlight=video > very low brightness, inverted controls and max brightness is too low

amdgpu.backlight=1 > max brightness stuck at 100% and heavy UI lag

amdgpu.backlight=0 nvidia_drm.modeset=1 > back to low brightness and inverted controls, UI lag has disappeared though

Is this a hardware issue or a kernel issue, but I am on the latest kernel. Also, secure boot is disabled if that’s relevant. Will masking one of the GPU systemd services work?

If anyone with similar device who has found out a fix for this it will be much appreciated.