Keyboard backlight keeps going on in Ubuntu 16.04 LTS

Question

I have just installed Ubuntu 16.04 LTS on my Dell Latitude E6540 and my keyboard backlight is keeps going on after some time even after I switch them off using the shortcut keys (Fn+->).
Thanks in advance for any help.

Answer 1

echo 2 | sudo tee /sys/devices/platform/dell-laptop/leds/dell\:\:kbd_backlight/brightness

Worked for me I have a new 2in1 Inspiron 7568.

Answer 2

Just purchased a 2016 Dell XPS13-9350. Wiped off Windows 10, with immense joy by the way, and installed Ubuntu 16.04 LTS and the Cinnamon desktop. This is a sweet laptop combo.

The default setting is to dim the keyboard back light after 10 seconds of no key press. This was driving me absolutely crazy because I fly a lot and want the back light to stay on longer.

The file /sys/devices/platform/dell-laptop/leds/dell\:\:kbd_backlight/stop_timeout contains the back light timeout value.

Answer 3 (above) did not work for me because the echo command did not work, even as root. Instead I did the following:

sudo nano /sys/devices/platform/dell-laptop/leds/dell\:\:kbd_backlight/stop_timeout 

change the 10s on line-1 to 300s (Without quotes). This will change the timeout to 5 minutes. Change it to whatever you wish.

Save the file (Ctrl-O, Enter, Ctrl-X).

Hope this helps someone as frustrated with this as I was.

Answer 3

I found fix in one of comments on launchpad bugtracker

Step 1: change system option

Edit file /etc/dbus-1/system.d/org.freedesktop.UPower.conf

change:

<allow send_destination="org.freedesktop.UPower"
       send_interface="org.freedesktop.UPower.KbdBacklight"/>

to:

<deny send_destination="org.freedesktop.UPower"
       send_interface="org.freedesktop.UPower.KbdBacklight"/>

Step 2: execute command with system startup

add folowing lines to the file /etc/rc.local

#!/bin/sh -e
# Mask kernel module
sudo systemctl mask systemd-backlight@leds\:dell\:\:kbd_backlight.service
exit 0

It is really works.

Keyboard backligt works too, but not automatically, by pressing Fn-keys only.

Answer 4

Another thing on Dell laptops (including my XPS 15, 9550) is that the backlight dims and goes off after 10 seconds idling.

There is a command that worked for me (Linux Mint 18 on a 9550, kernel 4.8) that allowed me choose the timeout :

sudo bash -c 'echo "60s" > /sys/class/leds/dell\:\:kbd_backlight/stop_timeout'

This is for a 60s timeout, which is sufficiant in my case. Of course, you can put anything here, like 3600s for an entire hour, which can comfortably relate to « stay on ».