Ubuntu 20.04.2 + Lenovo Legion 5 brightness (intel+nvidia)

About 1 week I can't fix my problem with last LTS Ubuntu. I have Lenovo Legion 5 (i7+1660ti). All works fine, but brightness control doesn't work at all. I've tried all fixes from forums and can't solve this problem. Last kernel didn't fix this problem. Also I tried last Ubuntu 21, Kubuntu, Pop!_OS - everywhere is the same problem. What I need - turn on intel graphics and turn off nvidia (so in BIOS need to be hybrid mode). I saw many fixes for AMD graphics, but not for intel. Any ideas?

By the way

  1. If I enable in BIOS Hybrid mode - I have the same brightness as in Windows by default in Ubuntu, without can't changing
  2. If I enable in BIOS Discrete mode - I have 100% brightness in Ubuntu, without can't changing

Solution 1:

have Lenovo Legion 5(Ryzen7 + RTX3060), using Pop!_OS 20.04, faced same problem.

I prefer to work on discrete card, so solved it with:

sudo kernelstub -a "nvidia.NVreg_RegistryDwords=EnableBrightnessControl=1"

After reboot my brightness control buttons started working as expected.