I cannot change the screen brightness

Question

here's my problem:

Ever since I installed Ubuntu 12.10 on my computer I haven't been able to change the screen brightness, it was always set to the maximum. I did take a look at this post:

Decrease Backlight Below Minimum

And it helped me resolved the issue with the unbearable brightness, however one problem persists: I cannot change it through "Brightness & Lock" or the function buttons (F2 and F3), when I press the buttons, the animation shows up but nothing happens. I tried the following:

http://www.refreshit.info/2012/08/solved-brightness-increase-and-decrease.html

It did nothing...

If it helps:

I have an HP-dv6 6185la, it has an ATI Radeon 6770M HD card and an Intel HD Integrated Graphics Card

It only detects the "Intel® Sandybridge Mobile"

Thanks in advance.

Answer 1

What worked for me was to change the /etc/default/grub file as follows:

• Press Alt + F2 and type gksudo gedit /etc/default/grub

• Find the line: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" and modify it to one of the following:

  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

  or

  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor" (try this if the first one doesn't work)

• Save and close gedit.

• Open a terminal (ctrl + alt + T) and type sudo update-grub
• Reboot your pc.

Answer 2

I was do the same as above.

It was do nothing.

Then I had to leave my g75VW and closed the lid.

I come back after a while then I opened the lid and then the backlight was working with F5/F6 as it should be…

Only the onscreen display not showing…

I tried again with lid closing and after a while open it and it still working..

Hope it's helps.

Answer 3

Try this, it helped me with intel gpu http://ubuntufixer.blogspot.com/2012/12/set-screen-brightness-at-start-up.html