I have a Toshiba Satellite R830 laptop with Ubuntu 12.04.1 64 bit. The Fn + F6 and Fn + F7 buttons adjust brightness until I put my laptop on sleep.
On wakeup they don't work any longer. Is there a solution or a workaround to this issue?
I found a better solution than the one selected above.
gksudo gedit /etc/default/grub.
GRUB_CMDLINE_LINUX_DEFAULT=and modify it as follows:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor".
More info here: https://wiki.ubuntu.com/Kernel/Debugging/Backlight
This solution no longer works on 13.10 and 14.04.
A solution that does is creating an xorg configuration file:
sudo touch /usr/share/X11/xorg.conf.d/20-intel.confto create the file.
sudo gedit /usr/share/X11/xorg.conf.d/20-intel.confto edit its content.
Section "Device" Identifier "card0" Driver "intel" Option "Backlight" "intel_backlight" BusID "PCI:0:2:0" EndSection
Log out and in again.
I had the same problem with a Toshiba Portege R935 in 12.04, and I discovered this (not so elegant) workaround:
as root (not with
sudo but actually changing user:
su root), change the value in
echo 2937 > /sys/class/backlight/intel_backlight/brightness
Warning: these values are not between
7 (as the ones in the other directory), but between
4539, or something like that.