I have a Packard Bell DOT S netbook. First I installed Ubuntu on it. I noticed that I couldn't use my brightness control buttons (F11 F12). I saw the little bar like it is changing its brightness, but actually it did nothing. Then I found a command line:
sudo gedit /etc/default/grub
And there I edited this line: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
After it just worked perfectly, but sadly my wifi went wonky and I couldn't use it actually on Ubuntu so I decided to get Lubuntu. Everything was fine with it, but still I cannot use the brightness buttons. I tried the previous method, but it just says: sudo: gedit: command not found
I looked for another solution, and I found this line:
sudo sed 's/GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"/GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi="/' -i /etc/default/grub
Before that, I saw the same thing as in Ubuntu: saw the bar is changing, but actually no change in the brightness. So I tried this method, rebooted, and now even that bar has disappeared.
At least help me to get back to the point I started. But ultimately I'd like to use my brightness control buttons!
sudo update-grub
You can also try 2 more parametersapci_osi=Linux
andacpi_backlight=vendor
Do not forget to update grub and and reboot for changes to take effect. Also acpi-support package is not installed in Lubuntu I think. Trysudo apt-get install acpi-support