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I have tried all relevant Settings choices, including "xset s off; xset s noblank; xset -dpms; xrandr --output HDMI-1 --brightness 1.0" as ordinary user and root, but the screen still dims itself occasionally at random. How can I permanently turn OFF screen dimming?

There must be some code in the Ubuntu installation to do this!

Maybe something in /etc?

John Williams
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  • I've got the same on Dell G15 5515 and Ubuntu 21.10, it just dims randomly without reason – Dmitry Dec 14 '21 at 20:38
  • The problem is in ubuntu power manager upower. But you cannot uninstall it, ubuntu isn't flexible like debian. I'll try to install xcfe4-power-manager on top of it and see if would help. – Dmitry Dec 14 '21 at 20:57

6 Answers6

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I have the same problem. I opened a bug on ubuntu's launchpad. Hoping they fix it.

Interestingly the bug stopped happening on this particular kernel version: 5.11.0-16-generic. Now it's back again.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1938477

Felipe Butcher
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  • Welcome to Ask Ubuntu! Be sure to only post real answers to the poster's question in the Answer section. – ldias Sep 09 '21 at 23:19
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    Even if this post doesn't provide a solution, I find it provides further valuable information. – Seven Oct 27 '21 at 08:21
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Based on the Ubuntu help-page, it seems there are some settings that you can check in the Power Saving section of the Power settings.

Per official Ubuntu helppage: https://help.ubuntu.com/stable/ubuntu-help/power-whydim.html.en

If it is possible to set the brightness of your screen, it will dim when the computer is idle in order to save power. When you start using the computer again, the screen will brighten.

To stop the screen from dimming itself:

Open the Activities overview and start typing Power.

Click Power to open the panel.


Switch the Dim Screen When Inactive switch to off in the Power Saving section.
Bish
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  • Thanks, but I've already run "Power" and tried all the displayed commands -- no matter what I do, my screen dims (including while running "power")! I need some info on HOW the various CLAIMED power-control commands control my computer. – John Williams Jul 25 '21 at 02:12
  • Have you seen this answer by @vanadium ? I assume you're using the default Ubuntu with Gnome, unless you're using another desktop environment?

    https://askubuntu.com/a/1346130/1074455

     – Bish Jul 25 '21 at 12:34
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    I tried running the four screen-disablers listed there - my screen still dims uncontrollably. There is something in my OS which is wrong, but I don't know what. I suspect there is something in /etc or /var involved . . .. – John Williams Jul 25 '21 at 17:52
  • I reinstalled Ubuntu (same v. 20.04.2 LTS), but the uncontrolled dimming STILL occurs. Power setting is "Blank Screen = never"; Screen Lock is "Blank Screen Delay = never", with everything else off. What controlls this screen dimming? There must be some command somewhere which can be disabled or removed! – John Williams Aug 05 '21 at 05:16
  • NOTE: I have no "Dim Screen When Inactive switch" in my Power directory, which has no "Power Saving" section. Can this section be installed somehow? – John Williams Aug 05 '21 at 05:20
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As this is a perspective hasn't been discussed yet in this post, you might just have a setting that you don't want. You may have automatic brightness on, which changes the brightness depending on how bright the space around you is. In my opinion, ubuntu isn't the best at it, and it doesn't do it smoothly. This is made for laptops, so if you have a desktop, it's pointless.

You can change this in the settings app, under brightness.

AlexFullinator
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Same problem here! Kubuntu 20.04 dims randomly, even I have all the power saving options disabled. I noticed some strange things in this behaviour:

  • When de screen dims, if I go to "Power saving" options, if I move slightly or touch a little bit the brightness slider (which is correctly set top right) and click Apply, the screen returns back to its normal brightness. Brightness slider
  • When the screen its also wrongly dimmed, if I increase the brightness using the function keys on my keyboard, it returns to its brightness, but from then on the brightness indicator keeps appearing randomly on screen. Brightness indicator I wonder if all the problem will be related to my Graphics card controller module: amdgpu. When I hadn't this module installed, my laptop was unusable: very low resolution and many other problems I don't remember. My graphics card is reported by lspci as a "Advanced Micro Devices, Inc. [AMD/ATI] Renoir (rev c3)"

Thanks.

JOAN S. SALELLES MATEU
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I am using kubuntu 22 and in my case I have detected that the system set dynamic contrast option in the configuration of my additional monitor. I uncheked the option and that corrects the dim behaviour.

Rosa Amelia Ocaña
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Editing /usr/share/X11/xorg.conf.d/10-quirks.conf to ignore Video Bus resolved the problem I had on Ubuntu Desktop 23.10 where my laptop LCD screen brightness changed randomly every few seconds.

Add the section below to /usr/share/X11/xorg.conf.d/10-quirks.conf

Section "InputClass"
        Identifier "Spooky Ghosts"
        MatchProduct "Video Bus"
        Option "Ignore" "on"
EndSection

I found this solution discussed here: random event changes screen brightness automatically

J.T.
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