Je cite le wiki d’ubuntu
- Backlight control does not work and there are no entries in /sys/class/backlight.
- Neither the ACPI backlight driver nor any vendor specific driver were able to find a valid interface. Either requires a new vendor driver (which is unlikely) or the ACPI BIOS is broken (see below). Updates to the ACPI BIOS are rare as well but in some cases it is possible to work with upstream to extend the Linux side to handle some of that brokenness.
Même pas sûr que le changement de noyau aide mais MdgRUN a connu une expérience heureuse.
Sinon, essayer ça : /usr/share/X11/xorg.conf.d/80-backlight.conf
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "AccelMethod" "sna"
Option "Backlight" "intel_backlight" # use your backlight that works here
BusID "PCI:0:2:0"
EndSection
réf : https://wiki.ubuntu.com/Kernel/Debugging/Backlight#Intel_HD_Graphic_Controllers