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I have been struggling now for an inordinate amount of time trying to get the brightness adjustment working in Ubuntu.

I am running Ubuntu 12.04 on a Lenovo V570 Laptop.

I have tried all of the adjustments I can find to "fix brightness control" in the /etc/default/grub file with the following results (before you ask, yes I did run sudo update-grub and sudo reboot after each change):

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi="

Result: No response to buttons, slider has no affect.

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

Result: No response to buttons, slider has no affect.

GRUB_CMDLINE_LINUX_DEFAULT="splash quiet acpi_osi='!Windows 2012'"

Result: Limited response to buttons from OS (slider only moves down one tick, then sticks), no dimming, slider has no affect.

GRUB_CMDLINE_LINUX_DEFAULT="splash quiet" Result: OS responds to buttons, but screen does not dim. Slider has no affect.

Am I missing something? What can I do to adjust the brightness?

Update: I did more searching, and I found that in /sys/class/backlight I have both acpi_video0 and intel_backlight. By changing the "brightness" file in each of these folders, I discovered, that editing the /sys/class/backlight/intel_backlight/brightness changed the actual brightness setting on my screen. How do I get Ubuntu to adjust this setting? Any hope of getting my function keys to also adjust it?

Update2:

As requested, here is the output from lspci:

    $ lspci | grep VGA
    00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
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marked as duplicate by Eric Carvalho, Charles Green, muru, KasiyA, minerz029 Nov 13 at 9:06

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

2 Answers 2

I had the same problem on my ThinkPad x240 running Ubuntu 14.04, and created a script that outputs and lets you step brightness up or down.

This assumes that the manual method of putting a number into /sys/class/backlight/intel_backlight works, so test that first:

sudo tee /sys/class/backlight/intel_backlight/brightness <<< 500
sudo tee /sys/class/backlight/intel_backlight/brightness <<< 300

The script is here:

https://gist.github.com/emning/5d3301a3f3c9420414f7

Save it as 'brightness' somewhere in your path, make it executable and run:

brightness
brightness up
brightness down

You can also bind these commands to shortcut keys, even the standard brightness keys seem to work fine. I used Custom Shortcuts in KDE, but any desktop environment should work.

NOTE: For this to work when using shortcut keys, sudo without password has to be enabled for your user.

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I was also suffering from same problem,but I found here a solution that worked for me(on Acer Aspire-5738).

If you have acpi_video0 and /sys/class/backlight/intel_backlight/brightness and changing /sys/class/backlight/intel_backlight/brightness is changing your computer brightness , you can force your system to use intel_backlight.

  • Create a file 20-intel.conf in /usr/share/X11/xorg.conf.d/ using following command:

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

  • Now paste this

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

  • Save and logout.

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I just attempted this, to no avail. After rebooting, I tried again to use the slider and the function keys to alter brightness. Neither had any affect. –  Bts Mar 2 at 17:29
    
you can use sudo tee sys/class/backlight/intel_backlight/brightness command temporarily to change your brightness using terminal or you can create a simple script having #/bin/bash sudo tee /sys/class/backlight/intel_backlight/brightness, make it executable and use it until a working solution is not found.. –  g_p Mar 2 at 17:39
    
Right, I am able to do it manually by using the method you mentioned. Are you saying that it is not possible to use the slider and/or function keys at this time? –  Bts Mar 2 at 17:42
    
Can you post the output of lspci | grep VGA. BusId in the above solution may need to change according to output. –  g_p Mar 2 at 18:23
    
See 'Update 2' above. –  Bts Mar 2 at 19:30

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