Comment 14 for bug 1485246

Erwin (erwin-gaubitzer-6) wrote :

I also have the NP770Z5E. What helped me was to change the grub kernel boot parameter to

acpi_osi=linux acpi_backlight=video

in /etc/default/grub (line GRUB_CMDLINE_LINUX_DEFAULT=) (I have Debian Linux). Hint was found at
https://wiki.archlinux.org/index.php/Backlight#Kernel_command-line_options

After command "update-grub" and reboot changing brightness was possible again.