Ubuntu 14.04 - brightness problem in HP hybrid laptop

Solution 1:

sudo gedit /etc/default/grub

find this line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

and change it to:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

and then: sudo update-grub

That works for my HP ProBook. Here is where i found the solution: http://www.techjail.net/solved-brightness-problem-in-ubuntu-12-04-precise-pangolin.html