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Thread: KDE screen brightness control issues

  1. #1

    Default KDE screen brightness control issues

    I seem to have found a problem with the way KDE desktop handles screen brightness. After some time of inactivity, the display dims and then eventually goes dark completely. When I move the mouse or press a key, the screen lights up, sometimes to full brightness, but sometimes not. Sometimes it lights up dimmed, but may eventually go back to full brightness, or it may stay dim. If I click "Show hidden icons" in the system tray, and select "Battery and Brightness", I sometimes find that the brightness slider bar changed itself to a lower setting. If I move the slider bar to maximum brightness, it sometimes goes full bright, but sometimes not, or it might take a long time to take effect.

  2. #2
    Join Date
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    Default Re: KDE screen brightness control issues

    Take a look at the Power Management settings, dimming the screen after a period of inactivity is normal.

    System Settings -> Power Management -> Energy Saving

    The not coming back to full brightness on mouse movement is not normal. That may require further investigation...
    Regards, Paul

    2x Tumbleweed (Snapshot: 20191018) KDE Plasma 5
    2x Leap 15.1 KDE Plasma 5

  3. #3

    Default Re: KDE screen brightness control issues

    Quote Originally Posted by tannington View Post
    Take a look at the Power Management settings, dimming the screen after a period of inactivity is normal.
    Of course.

    System Settings -> Power Management -> Energy Saving

    The not coming back to full brightness on mouse movement is not normal. That may require further investigation...
    The Power Management settings look as expected.
    What further investigation steps do you suggest?

  4. #4

    Default Re: KDE screen brightness control issues

    Quote Originally Posted by amblabs View Post
    What further investigation steps do you suggest?
    Create a new user, configure the brightness control there, see how behaves.

    Run Windows or Live Linux on the same computer; see how brightness behaves.

    I haven't seen this in computers, but in smartphones it is common: it is possible to set the screen brightness to auto, meaning that the screen brightness depends on illumination in the room. This almost always works miserably, unless expertly configured. It looks like you have a laptop. Maybe some engineer decided to "help" the user by saving his eyes from excessive brightness in the night. This behavior may be OS-independent. Look in BIOS. Also, try different illumination levels in the room as the laptop wakes up.

    Try to replace nouveau driver with nvidia driver or vice versa if you have nvidia graphics.

  5. #5
    Join Date
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    Location
    Norfolk, UK
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    Default Re: KDE screen brightness control issues

    Additionally, is this a new problem that has only recently (after an update perhaps) manifested itself, or has it always been a problem.

    There is also the possibility it may be a hardware problem with the back-light.
    Regards, Paul

    2x Tumbleweed (Snapshot: 20191018) KDE Plasma 5
    2x Leap 15.1 KDE Plasma 5

  6. #6

    Default Re: KDE screen brightness control issues

    Quote Originally Posted by tannington View Post
    Additionally, is this a new problem that has only recently (after an update perhaps) manifested itself, or has it always been a problem.
    This laptop used to only have Windows 7 installed on it. I shrank the Windows 7 partition and added partitions for Linux and swap for dual-boot, and recently installed openSUSE 15.0. The display dimming issue has been happening under openSUSE ever since it was installed, but no such problem happens when booted on Windows 7.

    There is also the possibility it may be a hardware problem with the back-light.
    I doubt it. No problems under Windows 7, as I said. Also, the brightness control sliderbar in the KDE system tray > "Battery & Brightness" menu seems to randomly change positions by itself. Seems like a software issue to me.

  7. #7

    Question Re: KDE screen brightness control issues

    Quote Originally Posted by amblabs View Post
    and recently installed openSUSE 15.0.
    Why didn't you install 15.1? Try booting from latest live opensuse.

  8. #8

    Default Re: KDE screen brightness control issues

    Quote Originally Posted by ZStefan View Post
    Why didn't you install 15.1? Try booting from latest live opensuse.
    I have been running 15.0 for only a few months. Installing a new OS version is a major time sink and hassle. I avoid doing that as much as possible. I have real work to do, rather than mess with the OS...

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