I'm trying to use Linux on a Toshiba P855 laptop. And I have one big problem: the screen brightness can't be changed, and stays at maximum.
Tried different distros, also tried many boot options in the
/etc/default/grub file, but no success. Currently I'm with Kubuntu 12.04, and the function keys for brightness don't work (they never did on any distro), so I'm able to use only the slider for the brightness. But even then - nothing really changes.
All is working on Windows. What's wrong here?
EDIT: Additional information
/sys/class/backlight I have a symlink:
toshiba -> ../../devices/LNXSYSTM: 00/TOS1900:00/backlight/toshiba/
and in that
toshiba folder I have:
subsystem -> ...
/proc/acpi/ I have: