I have a Lenovo Legion 5 15ARH05H and I'm trying to get the backlight control working. This is a laptop with an AMD APU and NVIDIA GPU. It works in a Hybrid graphics mode with both GPU on, or a Discrete graphics mode where only the NVIDIA GPU is on and the AMD one is disabled. I always run the laptop in Discrete mode. I have tried various NVIDIA driver versions, and was able to get the backlight working on kernel 5.9.1, but I have no idea what I did to my system, a few weeks later it stopped working and now I can't get it back. Tried various kernel versions too, kernel configs, etc, nothing, the backlight just doesn't work. It doesn't work either via the /sys/class/backlight device nor via the hardware keys. On Windows everything works fine. Every time I boot, I get this in dmesg: [ 1.057696] ACPI BIOS Error (bug): Could not resolve symbol [\_SB.PCI0.GP17.VGA.LCD._BCM.AFN7], AE_NOT_FOUND (20200717/psargs-330) [ 1.057753] ACPI Error: Aborting method \_SB.PCI0.GP17.VGA.LCD._BCM due to previous error (AE_NOT_FOUND) (20200717/psparse-529) [ 1.057806] ACPI Error: Evaluating _BCM failed (20200717/video-357) I believe this is related to the brightness control problem, can anyone shed a light on this? Regards, Pedro
