I’ve been having trouble controlling my Lenovo T410’s display backlight brightness under Ubuntu 10.10.
Using the nvidia driver from the restricted repositories, pressing the brightness control keys led to a short flicker at the desired brightness and then had the display return to a very low brightness. The only other options were a completely black screen and one at full brightness.
With the nouveau driver, I could not control the brightness at all. When I pressed the keys, the slider changed, but the backlight brightness did not differ.
This solution did not work. When I added “acpi_backlight=vendor” (using the nvidia driver) to the linux line in grub at boot, X would not start at all.
I downloaded the latest driver from nVidia, then removed the nvidia driver using:
sudo apt-get remove nvidia-*
After chmodding (+x) and installing the nVidia driver, the brightness controls still didn’t work. This post led to a solution. After I added the following line to xorg.conf in the “Device” section:
Option "RegistryDwords" "EnableBrightnessControl=1"
and restarted the X server, I could finally control the display brightness as desired.
