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NOT A POSSIBLE DUPLICATE: My question is not the same as Can't change brightness in Ubuntu 16.04 LTS because I have tried most of the solutions there and they didn't work.

Whenever I try to change the brightness using system settings -> brightness and lock -> brightness slider, moving the slider has no effect and when I close system settings, the slider goes back to the full brightness position.

enter image description here (move the brightness slider to minimum [has no effect] and close system settings)

enter image description here (reopen brightness and lock and the slider is back to full brightness)

The buttons on the keyboard have the same effect.

lspci:

00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 0b)
00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev 0b)
00:14.0 USB controller: Intel Corporation 8 Series USB xHCI HC (rev 04)
00:16.0 Communication controller: Intel Corporation 8 Series HECI #0 (rev 04)
00:1b.0 Audio device: Intel Corporation 8 Series HD Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 1 (rev e4)
00:1c.2 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 3 (rev e4)
00:1c.3 PCI bridge: Intel Corporation 8 Series PCI Express Root Port 4 (rev e4)
00:1d.0 USB controller: Intel Corporation 8 Series USB EHCI #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation 8 Series LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 8 Series SATA Controller 1 [AHCI mode] (rev 04)
00:1f.3 SMBus: Intel Corporation 8 Series SMBus Controller (rev 04)
06:00.0 Network controller: Qualcomm Atheros QCA9565 / AR9565 Wireless Network Adapter (rev 01)
07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101/2/6E PCI Express Fast/Gigabit Ethernet controller (rev 07)

lspci -nnk | grep -A2 VGA:

00:02.0 VGA compatible controller [0300]: Intel Corporation Haswell-ULT Integrated Graphics Controller [8086:0a16] (rev 0b)
  Subsystem: Dell Haswell-ULT Integrated Graphics Controller [1028:0651]
  Kernel driver in use: i915

ls /sys/class/backlight/:

dell_backlight  intel_backlight
Community
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nom
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2 Answers2

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Change the files /sys/class/backlight/xxx/brightness manually, where xxx are replaced by dell_backlight and intel_backlight, to figure out which interface is responsible for your backlight control.

To change the value in /sys/class/backlight/xxx/brightness open a terminal and run:

sudo bash -c "echo 5 > /sys/class/backlight/xxx/brightness;"

Then create /etc/X11/xorg.conf if not exists and add:

Section "Device"
    Identifier  "Card0"
    Driver      "intel"
    Option      "Backlight"  "xxx"
EndSection

After edit /etc/X11/xorg.conf reboot your system and let me know if it works. `

Hölderlin
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You can run this command that works for all graphics cards:

for gcard in /sys/class/backlight/* ; do sudo bash -c "echo 5 > $gcard/brightness" ; done

If your account has sudo privileges you can simply add the above oneliner to your ~/.bashrc and be done with it.

Update: However this may not work when you lock/unlock your laptop. In that case you can write a script let's say with the name ~/.brightnesss_adjuster.sh (and make it exectuable) with this content:

#!/bin/bash
dbus-monitor --session "type='signal',interface='org.gnome.ScreenSaver'" | ( while true
do read X
if echo $X | grep "boolean false" &> /dev/null; then
    for gcard in /sys/class/backlight/* ; do sudo bash -c "echo 5 > $gcard/brightness" ; done
fi
done )

And then add this line to your ~/.bashrc:

# brightness set up
~/.brightness_adjuster.sh &
mohammad moghaddam
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