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The brightness key (Fn + left/right arrows) on my Acer ASPIRE v15 laptop> on Ubuntu 16.04 LTS are not working.
I can control the brightness by changing the value of brightness by editing the file: /sys/class/backlight/intel_backlight/brightness

I want to connect the (Fn + arrow) key to a script which edits the value in the
above file. But acpi_listen does not detect the pressing of (fn + arrow(left or right)) key. Though, it is able to detect (fn + arrow(up or down)) keys for volume control.

How to get these keys detected for brightness control by the acpi?

Edit: Binding another keys(other than the (fn + arrow) and calling the script as non-acpi event forces me to run the script by placing it inside /etc/sudoers.d/ directory in order to avoid prompting for password at each press of the key. (as changing the value of brightness requires root permission).

Pablo Bianchi
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rack_jack
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2 Answers2

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At first we need some information about the video card. Just to make sure the right one is working. For example it is a APU (CPU+GPU in one processor). Intel or AMD does not matter. In my example it is an i5 470U processor. For further use we need the ID of the graphic card:

$ sudo lspci | grep VGA

--> 00:02.0 VGA compatible controller: Intel Corporation Core Processor 
    Integrated Graphics Controller (rev 02)
The ID is 0:2:0

For further information about the vide device use

$ sudo lshw -c video

We need to edit/create a config file for xorg:

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

For our example the following section has to be inserted:

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

Source: https://wiki.ubuntuusers.de/Grafikkarten/Intel/

Then the grub bootloader has to be edited to rewrite the list of supported OS. This Bios option was introduced during the time of windows vista.

Source: https://wiki.ubuntuusers.de/Bootoptionen/

Grub editieren and extend the following line with acpi_osi=Linux in

/etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux"

Close file and update grub

$ sudo update-grub

Reboot the System.

$ reboot

The keys (with the sun symbol) on your keyboard for regulating the brightness should work now.

simageye
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-1

In settings > Devices > Keyboards look for the hotkeys for controlling brightness. If your built in keys don't work, you can manually bind over them (Select the adjust brightness shortcut and press Fn + L/R)

Minty
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