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.

i don't know exactly if it was the update to 16.04 - but yesterday i noticed that my keyboard backlight stopped working - it will not light up :-( — Stefan Krüger s-light, May 09 '16 at 19:29
hm got it to work again: first allow normal user to write to file: sudo chmod a+w /sys/devices/platform/dell-laptop/leds/dell\:\:kbd_backlight/brightness than set brightness to other value than 0 (0..9 are valid for me) echo 9 > /sys/devices/platform/dell-laptop/leds/dell\:\:kbd_backlight/brightness — Stefan Krüger s-light, May 09 '16 at 20:11

score 12 · Answer 1 · edited Sep 10 '16 at 07:26

12

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

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

edited Sep 10 '16 at 07:26

David Foerster

36,264
56
94
147

answered Jun 09 '16 at 15:48

kleeman7

139
1
7

1

This sets the light to level 2. Turning the light off can be done by echoing 0 into this file. But anyway - this does not answer the question posted here. – Bach Aug 29 '16 at 08:48
for thinkpad the directory is: /sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight but I can't figure out what is triggering the backlight to turn on all the time – Jonathan Aug 29 '16 at 18:34

score 12 · Answer 2 · edited Sep 10 '16 at 04:35

12

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.

edited Sep 10 '16 at 04:35

Anwar

76,649

answered Sep 09 '16 at 22:35

Sopwith

121

1

If sudo nano FILE works, there's no reason why echo ... > FILE shouldn't work from a root shell. You probably ran sudo echo ... > FILE instead. See https://askubuntu.com/questions/230476/when-using-sudo-with-redirection-i-get-permission-denied. As such, your answer doesn't offer any improvement of the other answer. – David Foerster Sep 10 '16 at 07:23
I have been able to modify that file with nano but not with vim. Any idea why? With vim I got this error when trying :w "stop_timeout" "stop_timeout" E667: Fsync failed Press ENTER or type command to continue – Nisba Oct 08 '16 at 21:29
@Nisba I had the same problem with Neovim. I just used echo 5m | sudo tee ... as the first one mentions, but with this answer's file name. – Jonathan E. Landrum Apr 28 '17 at 01:56
1

This worked for me. Amazingly, I find I am unable to delete the file, or write using vi - even via "sudo"...yet I am able to edit using nano!!! How wierd is that?? – fig Jun 19 '17 at 21:14
@fig @Nisba the likely reason is because vi wants to make a temporary file in that directory, and nano doesn't. You can still write with vi, but exit with :x! to override the complaint about the temp file. – Jonathan E. Landrum Jan 18 '18 at 03:35

PRIHLOP · Answer 3 · 2017-05-26T22:04:48.650

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.

This worked for Dell Precision 7510 - Ubuntu 16.04.1. I have attempted other fixes but this seems to be the only one that worked for me. Thanks! — Mike, Jun 22 '17 at 15:04

score 3 · Answer 4 · answered Aug 16 '17 at 17:56

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 ».

cat /sys/class/leds/dell\:\:kbd_backlight/stop_timeout returned 10s which is the default - in case any1 needs it — Anand Rockzz, Jul 09 '18 at 06:01

score 1 · Answer 5 · answered Mar 20 '18 at 20:41

1

I used to have my Dell Vostro 3560 keyboard-backlight constantly turned on after reboot, even if I had it turned off. The fix was in /etc/UPower/UPower.conf. I changed IgnoreLid=false to IgnoreLid=true. That helped.

answered Mar 20 '18 at 20:41

Alex

11

score 0 · Answer 6 · answered Aug 25 '22 at 02:55

I have run into this problem on Ubuntu 22.04.1 with Mate.

Pressing <Fn>+<Space> is not permanent because Mate overrides the backlight setting when the screen is unlocked.
Tweaking systemd does not help.

Solution

I have solved the problem by doing the following:

Run gsettings list-recursively | grep --color kbd to find relevant settings. In the output, you will find these rows:

org.mate.power-manager kbd-backlight-battery-reduce true
org.mate.power-manager kbd-brightness-dim-by-on-battery 50
org.mate.power-manager kbd-brightness-dim-by-on-idle 75
org.mate.power-manager kbd-brightness-on-ac 100

Change kbd-brightness-on-ac to 0 and kbd-backlight-battery-reduce to false by running:

gsettings set org.mate.power-manager kbd-brightness-on-ac 0
gsettings set org.mate.power-manager kbd-backlight-battery-reduce false

Now the keyboard backlight will stay off when you unlock the screen.

Keyboard backlight keeps going on in Ubuntu 16.04 LTS

6 Answers6

Solution

Linked