I have a Toshiba Satellite C70D-A-114. It came with Windows 8, but very poor performance lead me to install Debian which has performed much smoother.
Unfortunately, none of the special function keys work after installing Debian. This creates a problem as the laptop being on 100% brightness makes it extremely uncomfortable to use, and I have no way of lowering it.
I have looked at a few solutions but can't seem to make any headway.
xrandr returns "failed to get size of gamma for output default" and /etc/default/grub contains the line 'GRUB_CMDLINE_LINUX_DEFAULT="quiet"'.
I have tried changing 'GRUB_CMDLINE_LINUX_DEFAULT="quiet"' to 'GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor" but it seemed to have no effect.'
If anyone might have a solution, please suggest it; I'd love to get this fixed.