I recently added Lubuntu to my Asus Eee 1005PE netbook. It's an excellent, lightweight distribution but, like practically all the other Linux distros I've tried on the Asus, the backlight control is flaky. Adjusting brightness via the keyboard's Fn+F5/F6 keys works, but in a non-linear fashion, and I could never seem to set it to maximum brightness unless it was plugged in.

This is a pretty common problem with netbooks, but it occurs to me the solution isn't well known. Here's the fix:

1. As root, edit /etc/default/grub and find the line begining GRUB_CMDLINE_LINUX_DEFAULT=

2. Add the commands acpi_osi=Linux acpi_backlight=vendor to the end of this line and save the file.

Before:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

After:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"

3. Run the command update-grub to rebuild the boot configuration.

4. Reboot. You should find you keyboard backlight controls work smoothly!


What it's doing

According to the Linux kernel parameters documentation:

acpi_osi=Linux
Tells the Advanced Configuration and Power Interface (ACPI) that the Operating System Interface (OSI) is Linux.

acpi_backlight=vendor
Tells the system to use the vendor-specific driver for the backlight instead of the system's default driver.