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Thread: Monitor doesn't stay in standby when using a DP cable

  1. #21
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    Default Re: Monitor doesn't stay in standby when using a DP cable

    If not reproducible with IceWM, report a bug to KDE's bug tracker and/or b.o.o. If it is, report it to the xorg-driver-ati mailing list, and optionally, report it at gitlab if you can't find an existing report there.
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  2. #22
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    Default Re: Monitor doesn't stay in standby when using a DP cable

    I logged into an IceWM session and used "xset dpms force standby" in an xterm console. The result was surprising: It seems to have worked and the monitor remained in standby for a few seconds, followed by properly powering back on and resuming the session once I pressed a keyboard key. I shall test this again when I have time to ensure it really is always working there.

    I remember the KDE Plasma Session was unable to put the monitor in standby over the DisplayPort cable on both X11 and Wayland. Only difference was that the X11 session simply had the monitor immediately coming back on after trying to enter sleep, whereas the Wayland session crashes to the login screen instead. I may try Plasma on X11 again to double-check that it still doesn't work there either.
    openSUSE Tumbleweed x64, KDE Framework 5

  3. #23
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    Default Re: Monitor doesn't stay in standby when using a DP cable

    Quote Originally Posted by MirceaKitsune View Post
    I logged into an IceWM session and used "xset dpms force standby" in an xterm console. The result was surprising: It seems to have worked and the monitor remained in standby for a few seconds, followed by properly powering back on and resuming the session once I pressed a keyboard key. I shall test this again when I have time to ensure it really is always working there.

    I remember the KDE Plasma Session was unable to put the monitor in standby over the DisplayPort cable on both X11 and Wayland. Only difference was that the X11 session simply had the monitor immediately coming back on after trying to enter sleep, whereas the Wayland session crashes to the login screen instead. I may try Plasma on X11 again to double-check that it still doesn't work there either.
    Firstly I don't have the same setup, I'm using a 4K DP connected monitor and a WUXGA (1920x1200) monitor, they're connected to a Nvidia GPU, and I'm using the proprietary driver with X11. But adding a DP monitor has introduced some annoying issues.

    I do experience a very similar problem to the one you've described. If my chrome browser contains a tab that is actively playing media (even an advert), after forcibly sending the monitor to sleep, it will shortly wake up again. Chrome uses some desktop mechanism that media players can use to keep a screen awake while playing media (you can see messages about it using journalctl). I find it safest to close most tabs or the entire browser if wanting to suspect my monitors from software. This is true for all connected monitors, it's not just a DP connected issue.

    One other possibility. After adding a DP connected 4K monitor I discovered that the hot-plugging behaviour around DP is very different than for HDMI or DVI. I wonder it some hotplug related bug might be causing your issue. For KDE-Plasma KScreen 2 deals with DP hot plug monitor events. KScreen 2 can be safely disabled if you're using a fixed (unchanging) monitor configuration. Disable Application Menu -> System Settings -> Workspace -> Startup and Shutdown -> Background services -> KScreen 2. (I've described my multi-monitor multi-DPI experience in another post.)

    Some monitors have a config setting that disables the sending of DP hotplug events so a DP connection will behave like an HDMI/DVI monitor.

  4. #24
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    Default Re: Monitor doesn't stay in standby when using a DP cable

    Quote Originally Posted by mchnz View Post
    Firstly I don't have the same setup, I'm using a 4K DP connected monitor and a WUXGA (1920x1200) monitor, they're connected to a Nvidia GPU, and I'm using the proprietary driver with X11. But adding a DP monitor has introduced some annoying issues.

    I do experience a very similar problem to the one you've described. If my chrome browser contains a tab that is actively playing media (even an advert), after forcibly sending the monitor to sleep, it will shortly wake up again. Chrome uses some desktop mechanism that media players can use to keep a screen awake while playing media (you can see messages about it using journalctl). I find it safest to close most tabs or the entire browser if wanting to suspect my monitors from software. This is true for all connected monitors, it's not just a DP connected issue.

    One other possibility. After adding a DP connected 4K monitor I discovered that the hot-plugging behaviour around DP is very different than for HDMI or DVI. I wonder it some hotplug related bug might be causing your issue. For KDE-Plasma KScreen 2 deals with DP hot plug monitor events. KScreen 2 can be safely disabled if you're using a fixed (unchanging) monitor configuration. Disable Application Menu -> System Settings -> Workspace -> Startup and Shutdown -> Background services -> KScreen 2. (I've described my multi-monitor multi-DPI experience in another post.)

    Some monitors have a config setting that disables the sending of DP hotplug events so a DP connection will behave like an HDMI/DVI monitor.
    I tested with all applications closed after a fresh login, the monitor still didn't properly go or remain in standby. I'm glad this signal exists since I wouldn't want to have to move the mouse every 5 minutes while watching a Youtube video... the signal likely wouldn't be interface specific however, and recently I discovered standby does work correctly under IceWM so this only happens under a Plasma session.

    Disabling KScreen2 is a very interesting suggestion, will give that a go next time I have an opportunity to test this. Is it enough to just use the "stop service" button and disable it in a running session then test the standby? Thanks for the useful idea.
    openSUSE Tumbleweed x64, KDE Framework 5

  5. #25
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    Default Re: Monitor doesn't stay in standby when using a DP cable

    Quote Originally Posted by MirceaKitsune View Post
    I tested with all applications closed after a fresh login, the monitor still didn't properly go or remain in standby. I'm glad this signal exists since I wouldn't want to have to move the mouse every 5 minutes while watching a Youtube video... the signal likely wouldn't be interface specific however, and recently I discovered standby does work correctly under IceWM so this only happens under a Plasma session.

    Disabling KScreen2 is a very interesting suggestion, will give that a go next time I have an opportunity to test this. Is it enough to just use the "stop service" button and disable it in a running session then test the standby? Thanks for the useful idea.
    Yes, the keep-awake facility is useful, I just keep getting burnt by media playing in browser tabs. After disabling KScreen I have the option of physically powering down my monitors without my windows moving about, so that's a pretty absolute solution. On the other hand turning off the monitors doesn't lower the power consumption of the CPU+GPU, I should try to get in the habit of closing the browser if I'm going away for a while.

    I'm not sure about whether stopping KScreen would be sufficient, I suspect yes. I tend to login/out (or even reboot) to make sure things have stuck and that other things I've tried haven't confused the situation.

    Note, I also mentioned a third possibility, which is that some monitors have a setting to disable DP hot-plug events, in which case they should behave just like an HDMI/DVI connected monitors. Perhaps that would cause Plasma to behave better.

    I can't imagine using IceWM, I've been using KDE for decades, but being fairly addicted to the command line, I suppose it doesn't make much difference.

  6. #26
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    Default Re: Monitor doesn't stay in standby when using a DP cable

    I can confirm that disabling hotplugging fixes this problem! After going to System Settings - Workspace - Startup and Shutdown - Background Services and disabling KScreen 2, I'm able to properly put my monitor into standby. This component is responsible for waking the monitor up immediately after it powers down even when you don't press a key or move the mouse.

    Note that this only fixes monitor standby for the X11 Plasma session, not Wayland which appears to be an unrelated issue! Even with KScreen2 disabled, I still get a session crash and taken back to the login screen when my monitor goes into standby over the DP cable, although standby via HDMI works in Wayland too.

    Due to this on top of numerous other issues, I've had to switch back to using the X11 session. I really wanted to stick to Wayland but at this stage it's far too buggy at least for KDE Plasma breaking too many functionalities.
    openSUSE Tumbleweed x64, KDE Framework 5

  7. #27
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    Default Re: Monitor doesn't stay in standby when using a DP cable

    Quote Originally Posted by albert12 View Post
    I am running xorg not wayland. I run using display port with a 165 Hz refresh rate and screen resolution of 2560x1440. I do not have any problem with suspending the monitor. GPU is a Vega 64.

    Silly question; are you using a Display Port cable that is D8k certified, or at least a version 1.4 cable?
    I believe I am. The package didn't contain a lot of information, all I have is this photo of the label if it helps any:

    openSUSE Tumbleweed x64, KDE Framework 5

  8. #28
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    Default Re: Monitor doesn't stay in standby when using a DP cable

    Quote Originally Posted by MirceaKitsune View Post
    I believe I am. The package didn't contain a lot of information, all I have is this photo of the label if it helps any:
    If I google ca-dpdp-10cc-0018-bk I can track down specs for a Lanberg brand cable:

    https://www.lambda-tek.com/Lanberg-C...y#product-view

    https://www.dateks.lv/en/cenas/kabel...-1-8m-4k-black

    This cable is not listed as certified at:
    https://www.displayport.org/product-...bles-adaptors/

    Googling about DP cables seems to indicate bad cables can cause problems. It's hard to get a feel for how widespread these problems are. Some pages assert bad cables can damage monitors. Cables are generally not too expensive, I guess it could not hurt to try a certified one (unless you buy one that's faulty). The above certification site has a drop down list of Manufacturers that can be used to narrow the selection down to what's locally available.

    It seems like we have pushed some technologies to where they are not as robust or are closer to the edge of what we can make reliably.

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