display brightness problem with ubuntu 13.04

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?

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)

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.

Find video/graphics card in Ubuntu and Linux Mint

Run the command below in terminal to know what video card is used for the backlight/brightness:

ls /sys/class/backlight/

find graphics driver in Ubuntu

As you can see, the output for me is dell_backlight and intel_backlight. An indicator that the graphics card in use is Intel. Another way to find out the graphics card would be to go in System Settings->Details->Graphics. You can see the graphic card in use.

If your graphics card is Intel, you can proceed with the fix below. Fix brightness control issue with Intel card in Ubuntu and Linux Mint:

Open a terminal and create the following configuration file, if it does not exist:

sudo touch /usr/share/X11/xorg.conf.d/20-intel.conf

Now we need to edit this file. You can use any editor be it a terminal one or graphical.

sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf

Add the following lines to this file:

Section "Device"
        Identifier  "card0"
        Driver      "intel"
        Option      "Backlight"  "intel_backlight"
        BusID       "PCI:0:2:0"

EndSection

Save it. Log out and log in back. The brightness control should be working through function keys now:

Fix brightness control not working in Ubuntu 13.10

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