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I had done a ton of reading on problems similar to this and have done some digging in my sys/class files to find my brightness controls. I found two possibles, one from Acer and one from Intel, both with varying results.

In each folder, there were a few files, three in particular being brightness, max_brightness, and actual_brightness. In the Acer backlight folder, all values read 15, but the value for brightness would change if I changed the brightness inside Ubuntu. So Ubuntu is trying to change the Acer brightness instead of the Intel brightness, which is next on our stop.

All values for the same three files read 976, and I could not change them no matter what.

Is there anyway to set Ubuntu to alter brightness for this backlight, instead of Acer's backlight?

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possible duplicate of brightness settings not ajustable – guntbert Oct 8 '13 at 19:06

1 Answer 1

up vote 0 down vote accepted

What usually works with this problem is the following press ctrl + alt + T to start a terminal type:

sudo gedit /etc/default/grub

find the line that says


change it to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"


sudo update-grub


if that doesn't work try this

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor acer_laptop.backlight=0"
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Thanks! That seemed to fix it! – Dr. Doctor Oct 9 '13 at 1:04

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