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I cannot adjust my laptop's brightness. What can I do?

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Have you tried adding the brightness applet to your desktop panel? –  Zoot Jan 30 '11 at 21:26
    
Have you tried this apps screensaver power maneger set screen brightness and uncheck the dim at idle –  antman1380 Jan 30 '11 at 23:41
    
Did you solve your problem? If so, please mark some answer as accepted or provide your solution. If not, please provide more info in your post (like how you tried to solve the problem). Thank you. –  sindikat Feb 25 '12 at 13:54

3 Answers 3

I also have an Acer laptop that would not adjust brightness properly.

The following worked for me.

Open up a terminal (Applications>Accessories>Terminal) and type the following in:

gksu gedit /etc/default/grub

This will as for your password and then bring up a text editor. Find the line with "GRUB_CMDLINE_LINUX" on it and make it so that it reads the following:

GRUB_CMDLINE_LINUX="acpi_osi=Linux"

Save the file, quit, then run the following in the terminal:

sudo update-grub

This will ask for your password again. Know that it is registering your keystrokes even though nothing looks like it's happening. Just put your password in and hit enter like normal.

Once the process is completed, restart your computer. It should allow you to change your brightness now.

Best of luck, and please come back if this doesn't work.

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This is usually an ACPI table bug. Install fwts from universe and run the full suite of interactive tests. At the end of the run you'll have a nice list of what works in your bios and what doesn't. Then file a launchpad bug using this data and take it from there. If you get a developer's attention, this can be triaged to the point where its easy for Acer to make the fix. Worst case, a custom DSDT table can be divined.

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echo <percentage> > /proc/acpi/video/VGA/LCD/brightness

Set laptop display brightness.

Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). cat /proc/acpi/video/VGA/LCD/brightness...

Source: http://www.commandlinefu.com/commands/view/7582/set-laptop-display-brightness#comment

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