Edit the grub bootloader configuration file: sudo nano /etc/default/grub
change the line: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" to: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"Again, type Control-X to exit, press the Y key and then press enter to save the file.
Update the grub bootloader configuration: sudo update-grub2 sudo reboot More informations here: https://trisquel.info/en/wiki/brightness-trisquel-mini-lxde-samsung-users
