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I have installed Ubuntu 13.04 and the proprietary AMD catalyst driver 13.4.

After installing the driver, the brightness of the screen has turned to the lowest and can not be changed. No matter how I scrolled the brightness bar, the brightness doesn't change.

I tried editing grub with acpi_backlight=vendor. But, it didn't work and the brightness hotkeys stopped working.

Note that Ubuntu 12.04 works perfectly without a single issue. What can I do to solve the problem in Ubuntu 13.04?

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Please add the model of your laptop to the question! – Jorge Castro May 1 '13 at 13:57

I had the same issue but have solved this by doing the following steps:

  • First, check your brightness operator by using the following command:

    ls /sys/class/backlight/*/brightness this will output like: /sys/class/backlight/dell_backlight/brightness /sys/class/backlight/intel_backlight/brightness(in my case).

  • Next, check your current brightness by using the following command:

    cat /sys/class/backlight/intel_backlight/brightness

    (replace intel_backlight to your backlight operator that was output in above command).this will output like455.

  • Now, check for maximum brightness:

    cat /sys/class/backlight/intel_backlight/max_brightness this will output like 4882

  • Now, your brightness could be from 0 to 4882 and you can adjust it by using the following command:

    echo 450 | sudo tee /sys/class/backlight/intel_backlight/brightness. (I have done it for saving my brightness 450).

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good answer thanks. :) – kumar_harsh Dec 6 '13 at 5:38

I had the exact same issue on a Dell Pavilion dv7 when upgrading from a Wonderful installation of 12.10 to 13.04 (so far "upgrade" is not really the description I'd use...)

Anyway, I had to edit /etc/rc.local and add:

echo 8 > /sys/class/backlight/acpi_video0/brightness

before the exit 0, then sudo chmod +x /etc/rc.local to make sure it gets run.

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