Hello,
I am using a Lenovo X1 Carbon Gen 12 Thinkpad (LENOVO 21KC000MUS). So far everything has worked well, but I cannot seem to get the backlight to work.
I do have a /sys/class/backlight directory, but there is nothing in it. After some light googling I found that sometimes kernel boot parameters need to be changed so I tried changing the line below in my configuration.nix.
boot.kernelParams = [ "acpi_backlight=vendor" ];
boot.kernelParams = [ "acpi_backlight=video" ];
boot.kernelParams = [ "acpi_backlight=native" ];
When I run sudo dmesg | grep acpi it returns the following for each of the kernel boot parameters.
For native and video it returns:
[ 0.000000] Command line: initrd=\EFI\nixos\842597lgwy8bd66dfnd80vl7yfw9am9y-initrd-linux-6.6.63-initrd.efi init=/nix/store/nlyarwxkkr3gajwbyn4dj6krgkvizwjn-nixos-system-nixos-25.05.20241207.22c3f2c/init acpi_backlight=native loglevel=4
[ 0.056961] Kernel command line: initrd=\EFI\nixos\842597lgwy8bd66dfnd80vl7yfw9am9y-initrd-linux-6.6.63-initrd.efi init=/nix/store/nlyarwxkkr3gajwbyn4dj6krgkvizwjn-nixos-system-nixos-25.05.20241207.22c3f2c/init acpi_backlight=native loglevel=4
[ 29.428438] thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver
For vendor it returns
[ 0.000000] Command line: initrd=\EFI\nixos\842597lgwy8bd66dfnd80vl7yfw9am9y-initrd-linux-6.6.63-initrd.efi init=/nix/store/sqdbg7mhxbl87jsxxrwq2kgsqd6zi0ra-nixos-system-nixos-25.05.20241207.22c3f2c/init acpi_backlight=vendor loglevel=4
[ 0.056796] Kernel command line: initrd=\EFI\nixos\842597lgwy8bd66dfnd80vl7yfw9am9y-initrd-linux-6.6.63-initrd.efi init=/nix/store/sqdbg7mhxbl87jsxxrwq2kgsqd6zi0ra-nixos-system-nixos-25.05.20241207.22c3f2c/init acpi_backlight=vendor loglevel=4
I am at my wits end here and any suggestions for what my next debugging steps should be would be greatly appreciated.
Thank you!