Bug 393223 - DisplayPort detection issues after standby/resume
Summary: DisplayPort detection issues after standby/resume
Alias: None
Product: KScreen
Classification: Plasma
Component: common (show other bugs)
Version: 5.12.4
Platform: Other Linux
: NOR normal
Target Milestone: ---
Assignee: Sebastian Kügler
Depends on:
Reported: 2018-04-17 13:01 UTC by Christian Muehlhaeuser
Modified: 2022-11-10 10:44 UTC (History)
3 users (show)

See Also:
Latest Commit:
Version Fixed In:

kscreen log (54.81 KB, text/x-log)
2018-04-17 13:01 UTC, Christian Muehlhaeuser

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Description Christian Muehlhaeuser 2018-04-17 13:01:53 UTC
Created attachment 112071 [details]
kscreen log

Note: I'm not sure if this is a kscreen bug or kwin bug, but I'm leaning towards the former.

I have two monitors connected to my system, one 1080p per HDMI, one 4k per DisplayPort. When putting my system to sleep (RAM), the DisplayPort connection seems to be shutdown in a weird way. Upon resuming from sleep, kscreen detects the DisplayPort monitor multiple times, which confuses kwin and a bunch of other applications (like latte-dock). Usually this manifests in the following ways:

- Only the HDMI monitor shows the lock-screen, the 4k/DP monitor only shows a black background (no lock-screen controls), but does show a mouse cursor when moving it to the screen.

- kwin loses window positioning and moves my windows from the HDMI monitor to the DP monitor.

- latte-dock sets an incorrect screen mask, making the right half of the dock disappear (see https://github.com/psifidotos/Latte-Dock/issues/941 for the upstream issue)

This is not happening every time I resume, but more often than not. It makes me assume this is a timing issues. Maybe the screen first gets initialized with 1080p, then quickly switches over to 4k?

Debug output from kscreen attached!
Comment 1 phrxmd 2021-11-09 16:19:41 UTC
I also have this issue when my monitor goes to Deep Sleep, upon wakeup the login screen appears on only one screen and my windows are a jumbled mess. This is with KDE 5.23.2
Comment 2 Nate Graham 2022-11-08 22:39:37 UTC
Thank you for the bug report. Unfortunately we were not able to get to it yet. Can we ask you to please check if this is still an issue with Plasma 5.25 or 5.26?

If it is, please add a comment with the output of `kscreen-doctor -o` and change the status to CONFIRMED. If not, or if you can't because you no longer use this setup, you can change the status to RESOLVED WORKSFORME. Thanks a lot!
Comment 3 Christian Muehlhaeuser 2022-11-10 10:44:35 UTC
In the meantime I have switched to entirely different hardware and only have one monitor. As such, I can't reproduce the issue any longer. I'll close this ticket as suggested. If someone else still runs into it, they can upon a fresh ticket with new logs.