Update to my previous comment - I've extensively tested different configurations (mostly kernel parameters) on my Legion 5 15ach6. I did manage to get the brightness to change when using just the dedicated GPU (selected as such within the BIOS,) using the parameter
nvidia.NVreg_RegistryDwords=EnableBrightnessControl=1 and this causes the nvidia gpu to show up in /sys/class/backlight/ alongside the amd one, but both of the /sys/class/backlight/*/brightness files do nothing. In hybrid mode and in integrated only mode (using optimus-manager to do it) acpi_backlight=video/vendor/native/none all do nothing, i tested each individually with amdgpu.backlight=1 and amdgpu.backlight=0, and did not get any hint of a way to control backlight, only the AMD iGPU showed up in /sys/class/backlight/, and changing the brightness value did nothing. Something else of note was that I noticed that when using just the dedicated NVIDIA card, xrandr showed DP-1 as the active montior, while when I was using the AMD iGPU, it was showing as eDP. Does anyone know if the MUX switch needs something from the kernel or nvidia driver to work properly? Is there any way for us to be able to check the position of the switch? -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1944094 Title: Can't adjust screen backlight on Legion Slim 7 / Legion 5 (2021) AMD To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1944094/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
