Bug 511490 - External monitor receives no input and causes laptop screen to freeze
Summary: External monitor receives no input and causes laptop screen to freeze
Status: RESOLVED DUPLICATE of bug 511216
Alias: None
Product: kwin
Classification: Plasma
Component: multi-screen (other bugs)
Version First Reported In: 6.5.1
Platform: Other Linux
: NOR major
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-11-02 00:50 UTC by laver323
Modified: 2025-11-07 20:57 UTC (History)
4 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:


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Description laver323 2025-11-02 00:50:30 UTC
SUMMARY
On my Thinkpad X1 Carbon 6th Gen., running KDE Plasma 6.5.1, after connecting an external monitor to the laptop, there is not video output to the external monitor, and the laptop screen freezes. After disconnecting the external monitor, the laptop screen then shows any activity you do (moving mouse, clicking on things). 

Essentially if you boot with an external monitor connected, you see a blank screen on both the external monitor and the laptop screen before it even gets to the login manager (SDDM). At that point unplugging the external monitor shows SDDM on the laptop screen.

If you login and plug the external monitor in again, it gets no video output and the laptop screen completely freezes till you unplug it again.

This issue occurred after the dnf upgrade from KDE Plasma 6.4.5 to 6.5.1 today on Fedora 43. It worked fine before that. I've tried connecting the monitor with both USB-C and HDMI (directly to the laptop). All output is shown during the Grub boot and in multi-user mode. Running "startplasma" in multi-user mode also then causes this.

STEPS TO REPRODUCE
1. Start KDE 6.5.1 with an external monitor connected with either USB-C or HDMI. Make sure the monitor is turned on and set to the correct input source.
2. Right when plasma would bring up SDDM, both the external monitor and laptop screen are blank.
3. Unplugging the external monitor brings up SDDM.
4. Log in on the laptop screen.
5. Plug in the monitor again.
6. You should see the external monitor not get video input, and the laptop screen won't reflect any mouse movements or typing.
7. Unplug the external monitor, and the laptop screen will no longer be "frozen".

OBSERVED RESULT
Cannot use an external monitor connected to a laptop with neither USB-C, nor HDMI. Trying to do so causes the laptop screen to freeze.

EXPECTED RESULT
I should be able to connect an external monitor.

SOFTWARE/OS VERSIONS
KDE Plasma Version: 6.5.1
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0

ADDITIONAL INFORMATION
Comment 1 laver323 2025-11-02 20:10:49 UTC
Note that the issue seems to be related to the type of monitor being used. I tested HDMI with another monitor with a 1920x1080 resolution and it works perfectly fine. This larger monitor with a 5120x1440 resolution is the one with an issue. If I try connecting this larger monitor after login and the display configuration is brought up, with HDMI, I get a message about gaps not being allowed in the display configuration.
Comment 2 laver323 2025-11-02 20:23:02 UTC
Just confirmed that the issue seems to be related to the horizontal resolution. I tried using pip mode on the larger monitor which had an issue, where two inputs can be shown on the screen, side-by-side, forcing a lower horizontal resolution for each of the inputs, and it all works well with plasma booting with a resolution of 2560x1440, using the left half of the monitor. It seems there's a regression with higher resolutions.
Comment 3 Stefan 2025-11-04 21:50:05 UTC
I also suffer from the problem described above by laver323.
The problem exists after plasma update to 6.5.1 and affects wayland.
X11 are fine. The wayland protocol under 6.5.0 works also well.
Initial I use the nouveau driver. The installation of the coresponding nvidia driver doesn't help.

1 The setup
-----------

I have tested various configurations/PC's.

Monitor:
        - 49" Samsung Monitor (C49HG90DMU)
PC's:
        - Dell XPS 15 9550 with Dell Dock WD19 or directly with hdmi (laptop) -> problem exists
        - Dell XPS 13 9305 (laptop) -> no problem
        - Self builded dekstop PC -> no problem

2 Evaluate the gpu's
-----------
With the following command I got the gpu's and the used driver:
lspci -k | grep -A 2 -E "(VGA|3D)"

Dell XPS 15 9550: Problem exists with multiple gpu and two displays
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06)
        DeviceName:  Onboard IGD
        Subsystem: Dell XPS 15 9550
--
01:00.0 3D controller: NVIDIA Corporation GM107M [GeForce GTX 960M] (rev a2)
        Subsystem: Dell XPS 15 9550
        Kernel driver in use: nouveau

Dell XPS 13 9305: No problem with one gpu and two displays
0000:00:02.0 VGA compatible controller: Intel Corporation TigerLake-LP GT2 [Iris Xe Graphics] (rev 01)
        Subsystem: Dell Device 0a5c
        Kernel driver in use: i915

Asus ROG CROSSHAIR X670E HERO with AMD Radeon 7900 XTX 24 GB (PowerColor Red Devil): No problem and multiple gpu, but only one display
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Navi 31 [Radeon RX 7900 XT/7900 XTX/7900 GRE/7900M] (rev c8)
        Subsystem: Tul Corporation / PowerColor Device 2422
        Kernel driver in use: amdgpu
--
6d:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Raphael (rev c9)
        Subsystem: ASUSTeK Computer Inc. Device 8877
        Kernel driver in use: amdgpu

3 Conclusion for my setup
-----------
It seems that the problem exists with more than one (high resolution) display (laptop + external) and more than one gpu.
I hope my information helps to find the problem and get a solution.

4 Log when plugged in the dp cable
-----------
04.11.25 21:38	kwin_wayland	failed to open drm device at ""
04.11.25 21:38	kwin_wayland	failed to open drm device at ""
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Applying output configuration failed!
04.11.25 21:38	kwin_wayland	failed to open drm device at ""
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Applying output configuration failed!
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Applying output configuration failed!
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Applying output configuration failed!
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Applying output configuration failed!
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Atomic modeset test failed! Das Argument ist ungültig
04.11.25 21:38	kwin_wayland	Applying output configuration failed!
04.11.25 21:38	kded6	Failed to notify "Created too many similar notifications in quick succession"
04.11.25 21:39	kded6	Failed to notify "Created too many similar notifications in quick succession"
Comment 4 Be 2025-11-06 05:40:06 UTC
I am also encountering this on a Lenovo Yoga 920-13IKB laptop with only an Intel integrated GPU. I have a 3840 x 2160 external LG 32UN550-W 2023 monitor connected via a USB-C to HDMI cable (the laptop has no HDMI ports to test with).

The bug doesn't manifest until a few seconds after the monitor is plugged in. The popup that usually appears when a screen is plugged in that lets me choose how to configure the displays does not get shown.

It is not just the display that freezes, but all keyboard input freezes too. This prevents switching to a TTY with Ctrl + Alt + F#. The only way to get the system to respond again is by unplugging the monitor or pressing the power button to shut down.

I installed GDM and switched to it (systemctl disable sddm && systemctl enable gdm, then reboot) for testing. GDM and GNOME both work fine with the external monitor plugged in. Trying to start a Plasma session from GDM with the external monitor plugged in fails. Logging in with the monitor unplugged then plugging in the monitor reproduces the freeze, so it is not just SDDM that is affected.
Comment 5 Be 2025-11-06 05:47:45 UTC
journalctl logs when plugging in my external monitor:

Nov 05 23:44:50 localhost-live.lan kernel: usb 1-6: new full-speed USB device number 13 using xhci_hcd
Nov 05 23:44:50 localhost-live.lan kernel: usb 1-6: not running at top speed; connect to a high speed hub
Nov 05 23:44:50 localhost-live.lan kernel: usb 1-6: New USB device found, idVendor=2141, idProduct=2141, bcdDevice= 1.00
Nov 05 23:44:50 localhost-live.lan kernel: usb 1-6: New USB device strings: Mfr=17, Product=18, SerialNumber=19
Nov 05 23:44:50 localhost-live.lan kernel: usb 1-6: Product: BillBoard Device
Nov 05 23:44:50 localhost-live.lan kernel: usb 1-6: Manufacturer: Realtek
Nov 05 23:44:50 localhost-live.lan kernel: usb 1-6: SerialNumber: 00000000000000000
Nov 05 23:44:51 localhost-live.lan kded6[2557]: Failed to notify "Created too many similar notifications in quick succession"
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Atomic modeset test failed! Invalid argument
Nov 05 23:44:51 localhost-live.lan kwin_wayland[2411]: Applying output configuration failed!
Nov 05 23:44:51 localhost-live.lan kded6[2557]: Failed to notify "Created too many similar notifications in quick succession"
Comment 6 rene 2025-11-06 14:11:21 UTC
Same problem and same error messages.
With 
> QT_LOGGING_RULES="kwin_wayland_*.debug=true"
I get the following:

>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Attempting to match QList(DrmConnector(id=114, gpu="/dev/dri/card1", name="DP-1", connection="Connected", countMode=42), DrmConnector(id=106, gpu="/dev/dri/card1", name="eDP-1", connection="Connected", countMode=1), DrmConnector(id=125, gpu="/dev/dri/card1", name="DP-2", connection="Disconnected", countMode=0), DrmConnector(id=132, gpu="/dev/dri/card1", name="DP-3", connection="Disconnected", countMode=0)) with QList(DrmObject(id=56, gpu="/dev/dri/card1"), DrmObject(id=80, gpu="/dev/dri/card1"), DrmObject(id=104, gpu="/dev/dri/card1"))
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Assigning CRTC 56 to connector 114
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Attempting to match QList(DrmConnector(id=106, gpu="/dev/dri/card1", name="eDP-1", connection="Connected", countMode=1), DrmConnector(id=125, gpu="/dev/dri/card1", name="DP-2", connection="Disconnected", countMode=0), DrmConnector(id=132, gpu="/dev/dri/card1", name="DP-3", connection="Disconnected", countMode=0)) with QList(DrmObject(id=80, gpu="/dev/dri/card1"), DrmObject(id=104, gpu="/dev/dri/card1"))
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Assigning CRTC 80 to connector 106
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Attempting to match QList(DrmConnector(id=125, gpu="/dev/dri/card1", name="DP-2", connection="Disconnected", countMode=0), DrmConnector(id=132, gpu="/dev/dri/card1", name="DP-3", connection="Disconnected", countMode=0)) with QList(DrmObject(id=104, gpu="/dev/dri/card1"))
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Attempting to match QList(DrmConnector(id=132, gpu="/dev/dri/card1", name="DP-3", connection="Disconnected", countMode=0)) with QList(DrmObject(id=104, gpu="/dev/dri/card1"))
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Attempting to match QList() with QList(DrmObject(id=104, gpu="/dev/dri/card1"))
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Atomic modeset test failed! Invalid argument
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Testing CRTC assignment... failed
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Assigning CRTC 104 to connector 106
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Attempting to match QList(DrmConnector(id=125, gpu="/dev/dri/card1", name="DP-2", connection="Disconnected", countMode=0), DrmConnector(id=132, gpu="/dev/dri/card1", name="DP-3", connection="Disconnected", countMode=0)) with QList(DrmObject(id=80, gpu="/dev/dri/card1"))
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Attempting to match QList(DrmConnector(id=132, gpu="/dev/dri/card1", name="DP-3", connection="Disconnected", countMode=0)) with QList(DrmObject(id=80, gpu="/dev/dri/card1"))
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Attempting to match QList() with QList(DrmObject(id=80, gpu="/dev/dri/card1"))
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Atomic modeset test failed! Invalid argument
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Testing CRTC assignment... failed
>nov 06 15:02:00 xps15-fedora kwin_wayland[2647]: Assigning CRTC 80 to connector 114

where this stands out to me:
>Attempting to match QList() with QList(DrmObject(id=80, gpu="/dev/dri/card1"))
It seems that the first QList is empty so it can't match? I'm not a developer so I might draw the wrong conclusion here.

Also, I am running both a built-in screen @ 3840x2160 and two external displays at the same resolution.
With the earlier statement that it's happening if the external display has a higher resolution than built-in, it seems that the built-in resolution is irrelevant.
Comment 7 Zamundaaa 2025-11-06 14:29:33 UTC
Does this still happen with Plasma 6.5.2? This looks like the same as bug 511216
Comment 8 rene 2025-11-06 16:20:59 UTC
Tested 6.5.2 using brand new packages in fedora/testing.
Problem seems fixed!
Comment 9 Be 2025-11-06 16:39:47 UTC
(In reply to rene from comment #8)
> Tested 6.5.2 using brand new packages in fedora/testing.
> Problem seems fixed!

`dnf update --enablerepo=updates-testing` tries to install 6.5.1 still. How have you installed 6.5.2?
Comment 10 Zamundaaa 2025-11-06 17:38:26 UTC
Cool

*** This bug has been marked as a duplicate of bug 511216 ***
Comment 11 rene 2025-11-06 18:01:40 UTC
(In reply to Be from comment #9)
> (In reply to rene from comment #8)
> > Tested 6.5.2 using brand new packages in fedora/testing.
> > Problem seems fixed!
> 
> `dnf update --enablerepo=updates-testing` tries to install 6.5.1 still. How
> have you installed 6.5.2?

https://bodhi.fedoraproject.org/updates/FEDORA-2025-252596f5da

Install bodhi-client, download rpms using

> bodhi updates download --updateid FEDORA-2025-252596f5da
Comment 12 Be 2025-11-07 03:42:21 UTC
I confirm the bug is fixed in kwin-6.5.2-1.fc43.x86_64
Comment 13 laver323 2025-11-07 05:10:52 UTC
I also just updated Fedora 43 with the Plasma 6.5.2 package updates, and can confirm that the issue is now resolved. 

Thank you all for also reporting having the issue and posting logs, and to the developers for fixing the issue.
Comment 14 Stefan 2025-11-07 20:57:53 UTC
On Arch the new version found the way into the repo. It works now, the problem was fixed succesfully. Thank you very much.