Kernel 6.1 breaks brightness control

I updated my kernel to 6.1 and after rebooting my laptop Toshiba satellite L750, I noticed that the brightness is too high so I decided to decrease it, but it didn’t work, not with the GUI because it didn’t exist and not with he hardware options

After some digging on the problem I read an old blog that said kernel 6.1 breaks brightness control for old laptops, so I decided to reboot it and use an older kernel, 6.0 and the brightness control worked again.

Also old iMacs like mine, but I can use ddcutil. The man page says:

       ddcutil does not support with laptop monitors, which do not implement DDC/CI.

This sentence isn’t very clear, but has a way to see if ddcutil can be used to control brightness on your system.

Hi Mohammad - I had a similar issue pop up on my machine, although mine is an AMD (yours appears to be Intel based on the model?) - for mine, adding amdgpu.backlight=0 to the end of the GRUB_CMDLINE_LINUX line in the file /etc/default/grub (using sudoedit from the terminal) did the trick, but it may be different for devices with Intel CPUs/integrated graphics?

Some of the parameters listed in the “Kernel command-line options” section of this page might be helpful to try?