You can also try this which worked with my Asus Eee PC 1005PE:
Modify your /etc/default/grub configuration file to include acpi_osi=Linux
parameter on the GRUB_CMDLINE_LINUX_DEFAULT line and reboot. So, if it looks
like this:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
Make it look like this:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux"
Could you also add your laptop to www.h-node.org, please? It would help a lot
especially if your laptop works fine with free software. Add a notice to the
description about the screen brightness problem and a solution if you found
one.
Please add your laptop even if it does not work well with free software.
Devices like that are important to report so that others can avoid them.
