Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

After 13.04 update the brightness control and even brightness in setting have stopped working. The brightness is on full and doesn't decrease. So far sound and wifi is working. Any settings or parameters that can be useful ? Even on suspend laptop is not going on sleep mode. This was working on 12.10

share|improve this question
Check this -… – mac Jun 28 '13 at 5:13

Try using this boot parameter apci_osi='!Windows 2012'

`sudo sed -i "s/quiet splash/quiet splash acpi_osi=\'\!Windows 2012\'/" /etc/default/grub;sudo update-grub`

if it makes things worse run this

`sudo sed -i "s/ acpi_osi=\'\!Windows 2012\'//" /etc/default/grub;sudo update-grub`
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.