Ubuntu 14.04 Dell Inspiron 15R - unable to adjust brightness

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Answer: 1

33 hours ago

When trying to adjust brightness on my Dell Inspiron 15R, I see the brightness icon moving up or down, but the actual brightness remains the same.

Added by: Donna Conn

Answer: 2

17 hours ago

I am using Dell Inspiron 15R N5520 with dual boot Windows 8.1 and Ubuntu 14.04 LTS.

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

    ls /sys/class/backlight/
    

    If your graphics card is Intel, you can proceed with the fix below.

  2. 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.

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

Added by: Rebeka Sanford

Answer: 3

27 hours ago

This problem was solved when I upgraded to 14.10

Added by: Ethel Ruecker IV

Answer: 4

9 hours ago

I realize you don't have a Gateway NE56R, but there is a solution (source: http://talegari.wikidot.com/blog:14) that may help you. If it doesn't, just undo the changes. First, open a terminal and type sudo gedit /etc/default/grub. You will (hopefully) see two lines: GRUB_CMDLINE_LINUX_DEFAULT="quite_splice and GRUB_CMDLINE_LINUX_DEFAULT="". I want you to comment them both out by putting a # at the beginning of each of the two lines. Then put the following line (not commented!) underneath:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force acpi_backlight=vendor"

Once you are done doing that, close gedit, and run one more command in the terminal:

sudo update-grub and reboot. If it works, hooray! If not, open up the file, uncomment the two lines, remove the line I told you to put in, close it, run sudo update-grub and reboot to undo what we have done. This is a little hardware compatibility bug that is fixed in 14.10 Utopic Unicorn, which doesn't come out until late October.

Added by: Susana Rempel

Answer: 5

21 hours ago

I wrote a small script which I use to control the brightness. Basically you want to poke a value into /sys/class/backlight/intel_backlight/brightness. The max value can be found in /sys/class/backlight/intel_backlight/max_brightness

My simple script is:

#!/bin/bash
echo $1 | sudo tee /sys/class/backlight/intel_backlight/brightness

An alternate answer is suggested by itsfoss, however I had to modify it slightly as the pci bus ID seems to have changed since Ubuntu 13.10:

Create the file 20-intel.conf

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

Edit the file so that the contents are

Section "Device"
        Identifier  "card0"
        Driver      "intel"
        Option      "Backlight"  "intel_backlight"
        BusID       "PCI:0:02:0"
EndSection

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