Found a workaround for my Toshiba Tecra A11: http://ubuntuforums.org/showthread.php?t=2275437&p=13272746#post13272746
TL;DR edit /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT="quiet acpi_backlight=vendor"
Found a workaround for my Toshiba Tecra A11: http:// ubuntuforums. org/showthread. php?t=2275437& p=13272746# post13272746
TL;DR LINUX_DEFAULT= "quiet acpi_backlight= vendor"
edit /etc/default/grub
GRUB_CMDLINE_