Laptop display no longer turning off at lowest brightness

gsingh93 · 2014-11-04 01:05:21

As of updating my system a week or two ago, I can no longer completely turn of my laptop monitor with the backlight keys. Before, the lowest brightness setting would be a completely black monitor, but now the lowest brightness is just a dim screen. I'm not sure if this has to do with some kernel update or my desktop environment, GNOME 3. One thing that might be important, is that `xbacklight -set 0` used to turn the display off, but now it also just puts it at the lowest brightness.

Does anyone know why this is happening?

markzz · 2014-11-04 05:45:51

I noticed this myself, but it seems that X no longer allows this to happen, which disappoints me and yet is a minimal problem.

mauritiusdadd · 2014-11-04 08:27:34

Hi gsingh93,

first of all, xbacklight cannot completely turn off your monitor: all it can do is to set the brightness level to its minimum value (and this can result in a very very dark screen) but it will leave the lcd turned on. If you want to switch off your monitor you should follow the ArchWiki instructions).

Now, can you provide the output of the following commands?

xbacklight -set 0 && xbacklight -get

Also, what is the graphics card of your laptop? It is a dual GPU system or it has only an integrated one?
Does it work if you manually set the backlight level to zero using a command like the following?

tee /sys/class/backlight/$your_backlight/brightness <<< 0 #this must be run as root
cat /sys/class/backlight/$your_backlight/brightness

where the value of $your_backlight depends on your graphics card model (again take a look to the ArchWiki)

@markzz

markzz wrote:

...but it seems that X no longer allows this to happen...

It is not true, xbacklight can set the brightness level to zero on my Samsung NP530U3C-A03IT with an integrated intel graphics card and my system is fully upgraded.

gsingh93 · 2014-11-04 19:01:31

`xbacklight -set 0 && xbacklight -get` returns 0. Also, `cat`ing `/sys/class/backlight/intel_backlight/brightness` at the lowest brightness shows 0. I really did like being able to turn off my monitor with the brightness keys, but I guess I'll have to settle for `xset dpms force off`, even though pressing a key or moving the mouse turns the monitor back on

mauritiusdadd · 2014-11-05 10:19:55

If you want the monitor to stay turned off even when you press a key or you move the mouse, you can use vbetool:

vbetool dpms off

The the downside is that the command has to be run as root, however you can install sudo and configure it to execute vbetool without requiring the password (some examples are available here), then you can use xbindkeys to bind the vbetool command to a combination of keys: for example, by adding the following entries into ~/.xbindkeysrc you will be able to switch on and off your monitor pressing respectively Shift + XF86MonBrightnessUp and Shift + XF86MonBrightnessDown.

"sudo vbetool dpms on"
  XF86MonBrightnessUp+Shift
"sudo vbetool dpms off"
  XF86MonBrightnessDown+Shift

Arch Linux

#1 2014-11-04 01:05:21

Laptop display no longer turning off at lowest brightness

#2 2014-11-04 05:45:51

Re: Laptop display no longer turning off at lowest brightness

#3 2014-11-04 08:27:34

Re: Laptop display no longer turning off at lowest brightness

#4 2014-11-04 19:01:31

Re: Laptop display no longer turning off at lowest brightness

#5 2014-11-05 10:19:55

Re: Laptop display no longer turning off at lowest brightness

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