I've installed Ubuntu 12.04 on my Toshiba Satellite L645D and the screen brightness does not work. Any suggestions?
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This http://askubuntu.com/a/214145/27968 worked for me. – To Do Nov 07 '12 at 15:28
2 Answers
You might want to edit your xorg.conf configuration. In a terminal, type:
sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.backup
This will make a backup of your xorg.conf file - just in case :) That being done, type:
gksudo gedit /etc/X11/xorg.conf
and under Section "Device" add the following line:
Option "RegistryDwords" "EnableBrightnessControl=1"
Save and reboot.
Perhaps this already does the trick. In that case, congratulations!

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I know it is a bit late but I had the exact same problem with my girlfriend's computer, a Toshiba Satellite L645D with Ubuntu 14.04 LTS. I think this fix should also work on this computer model with other Debian-related Distros.
After searching and trying everything in the web I found this page:
Keybinding to change brightness by way of acpi brightness file?
So what I did to fix the problem was open /etc/default/grub with nano (or whatever text editor you may like):
sudo nano /etc/default/grub
And search the line that starts with: GRUB_CMDLINE_LINUX_DEFAULT="(something)" I don't remember exactly what text it had on the quotes. And make it look like:
GRUB_CMDLINE_LINUX_DEFAULT="acpi_osi=Linux acpi_backlight=vendor"
Then update the grub with:
sudo update-grub
Finally, reboot and that's it! Hope that helps :D

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