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I have a Dell Inspiron 5520 with intel core i7 and AMD Graphics card. It used to work fine with Ubuntu 12.04 and Ubuntu 12.10. Now I tried to install Ubuntu 13.04 but i can't change display brightness: the FN keys don't change it, the indicator shows it always almost full, but won't change, won't increase or decrease. The same problem is there for both x86 and amd64 versions of Ubuntu.

What's the problem?

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7 Answers

I had the same problem, and solved after put this line:

GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

in /etc/default/grub file, and after:

# update-grub && reboot

I have one Dell Vostro 3560 running Ubuntu 13.04 x86_64 kernel 3.8.0-19-generic

And I'm using generic X.Org video driver (opensource, tested)

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Thanks, this doesn't work with Nvidia but I went back to the X.org driver and brightness controls work now! –  Elijah Lynn Jul 17 '13 at 1:58
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The following fixed the problem in my Acer laptop.

Open etc/default/grub with a root text editor

sudo -H gedit /etc/default/grub

Change

GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

to

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

After this run sudo update-grub and restart the system.

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i have the same issue in lenovo G580,

but I resolved it by editing grub,

/etc/default/grub file

and put this line in the end

GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

and after that update the grub,

 update-grub

and done

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I assume you installed the amd driver already (dash -> software sources -> last tab)

ubuntuforums.org/showthread.php?t=2139397
look at the kernel boot parameters
the file to edit is /etc/default/grub
after editing run sudo update-grub and reboot

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I got the same issue on Asus Zenbook UX32VD but I've solved by adding a comment mark # before the following line in /etc/default/grub file:

GRUB_CMDLINE_LINUX="acpi_backlight=vendor"
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same problem with hotkeys for display brightness on HP Elitebook 2170p with core i7 and Intel HD Graphics 4000 (Ubuntu 13.04)

for ubuntu-beginners the step by step manual in post #7 (by serdotlinecho) shall be very helpful:

http://ubuntuforums.org/showthread.php?t=2136133

greez!

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Welcome to Ask Ubuntu! Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. –  Kevin Bowen Sep 10 '13 at 9:10
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GRUB_CMDLINE_LINUX_DEFAULT="splash quiet acpi_osi='!Windows 2012'"

this works out best with most laptops having this issue including my ASUS K55VM. Its from Ubuntu Zenbook prime wiki https://help.ubuntu.com/community/AsusZenbookPrime

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