My OS is Ubuntu 22.04.2, kernel version is 5.19.0-45-generic, I use 530.41.03 NVIDIA driver. As I found out, NVIDIA uses its own files for brightness settings, which are stored at the path /sys/class/backlight/nvidia_0/ and the brightness value can be set in the range from 1 to 100. When starting the system, I have a brightness of 10, which is recorded in the file brightness and this value is actually the maximum brightness. However, if for instance I set the brightness value to 11, then this will actually become the minimum brightness value, and by increasing the value to 100, I will again reach the maximum brightness. Thus, I have a duplicate brightness ranges from 1 to 10, and from 11 to 100. I can still change the brightness setting via the interface, or using the FN key, however, if I reduce the brightness value once after the system starts, I will actually get from the maximum value, a value of 50% (5/100). And in the same way, if I increase the brightness 1 time, I will get from the maximum value, a value of ~5% (15/100). I guess I could adjust the minimum brightness value to 11 by creating a min_brightness file, since there is a max_brightness file with a value of 100, however I don’t have permission to check this. Is there any way to fix this?
I have this exactly same problem. I am using a laptop that has a MUX Switch and this happen when the MUX Switch is set to NVIDIA-only. The file brightness and actual_brightness are different from each other, looks like the NVIDIA driver is interpreting 100 as 10.0 and 45 as 4.5, but the value 4 is interpreted as 4.0, that’s the reason why 4 and 40 have the same brightness.
The problem was solved after updating the drivers to version 535