Brightness Hot Keys not working on Lenovo laptops running Ubuntu 12.10 Quantal Quetzal or Ubuntu 12.04 Precise Pangolin is a classic issue.
In this article I will show you how to fix the brighness hot keys issue on Lenovo IdeaPad Yoga permanently.
This worked also on a Lenovo ThinkPad X1 Carbon and Lenovo ThinkPad T430 running Ubuntu.
All you have to do is:
Open /etc/default/grub file in your favourite text editor, with root privileges:
$ gksudo gedit /etc/default/grub
Modify the following line:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
To look like this (Add acpi_backlight=vendor in the quotes, after quiet splash):
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
Blacklist “ideapad_laptop” (thanks savagejen) for the tip:
$ sudo sh -c 'echo "blacklist ideapad_laptop" >> /etc/modprobe.d/blacklist.conf'
Update grub, in order to apply the new setting
$ sudo update-grub
This is it. Reboot and Enjoy.