Comment 71 for bug 935778

Just got a Z930 and cannot change display brightness at all.

Set acpi_backlight=vendor in /etc/default/grub which resulted in displaying a widget that shows the "current" setting for display brightness and the change when I press FN-F6 or FN-F7 but the display itself remains at full power.

Creating /etc/udev/rules.d/00-tosh-backlight.rules and resulted in a black screen at login that I could not change at all.

Runninng Kubuntu 13.04 with latest updates as of today:
Linux mamo 3.8.0-23-generic #34-Ubuntu SMP Wed May 29 20:22:58 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux