Bug 507151

Summary: kwin treats HDMI TV as enabled and primary display when the TV is turned off and unavailable in settings
Product: [Plasma] kwin Reporter: antonio <antdev66>
Component: multi-screenAssignee: KWin default assignee <kwin-bugs-null>
Status: REPORTED ---    
Severity: normal CC: kdedev, nate, xaver.hugl
Priority: NOR Keywords: multiscreen
Version First Reported In: 6.3.6   
Target Milestone: ---   
Platform: Debian unstable   
OS: Linux   
Latest Commit: Version Fixed In:
Sentry Crash Report:
Attachments: display configuration with active monitor and TV
drm_info output

Description antonio 2025-07-17 09:19:15 UTC 
Hi,
I have a Debian PC with a Plasma 6 and the following screen configuration:
- Philips monitor connected to the Display Port
- LG TV connected to the HDMI port

I noticed that when I turn on the PC and SDDM starts to enter my login credentials, if I move the mouse to the left edge, the cursor disappears (this tells me that the PC monitor is treated as a secondary screen on the right, and the TV, even when turned off, is considered the primary screen).

However, if I run xrandr, it appears to be the only available and primary output:

$ xrandr
Screen 0: minimum 16 x 16, current 1920 x 1080, maximum 32767 x 32767
DP-1 connected primary 1920x1080+0+0 (normal left inverted right x-axis y-axis) 476mm x 268mm
  1920x1080 59.96*+
  ...
  ...

In the applet that configures the displays, all the icons are disabled (this is correct because there is only one active screen).

However, the audio through the monitor speakers (display port) is not heard, even though it is active, both from the plasma and from pavucontrol (once again, this confirms that the primary monitor is treated as a secondary screen).

Login with x11/Wayland: same behavior

To fix it, I had to unplug the TV's HDMI cable and reboot. Everything worked fine. On the login screen, the mouse cursor no longer goes off the edge, and audio through the monitor speakers is heard correctly. In this situation, if I reconnect the TV (HDMI port), the audio continues to work if I select "HDMI digital stereo output" instead of "HDMI2 digital stereo output" in the volume applet profiles (the TV is still off, however, the option to select both the audio output and the internal/external display to use appears). If I leave the TV connected and restart it, everything goes back to normal and the problem recurs: the monitor is again interpreted as a secondary display, the audio through its speakers is not heard, and the profiles only list the option "HDMI2 digital stereo output" (so I have no option to change the "HDMI digital stereo output" setting).

It's not the kernel: I checked by booting OpenSuse, which I installed on another partition with the same kernel, and everything works fine (even with the TV connected). However, the versions of QT, Plasma, etc., vary.

I don't think the problem is with Plasma, since it occurs before the desktop has even started, so only sddm remains, where moving the mouse off the left edge highlights the problem.

The problem is that the system confuses the internal and external monitors, that it intercepts the TV even if it is off and that it arbitrarily assumes that it is the main screen, despite the screen configuration in which I indicate the monitor as primary, and consequently the audio does not reach the monitor's speakers.

Thanks,
Antonio

SOFTWARE/OS VERSIONS
KDE Plasma Version: 6.3.6
KDE Frameworks Version: 6.13.0
Qt Version: 6.8.2
Graphics Platform: Wayland
Comment 1 antonio 2025-07-17 09:28:47 UTC 
The problem is also solved by unplugging the TV, logging off and then logging in to access the desktop again.
Comment 2 TraceyC 2025-07-21 19:30:24 UTC 
Thanks for the bug report. I'd like to ask you for a couple of details.

First - When both displays are (actually) enabled, in Display Configuration - can you confirm which display you have set to be primary?

Second - can you run the following in a terminal and paste the output into a reply in this report?

kscreen-doctor -o

Thanks again.
Comment 3 antonio 2025-07-21 19:54:52 UTC 
(In reply to TraceyC from comment #2)
> Thanks for the bug report. I'd like to ask you for a couple of details.
> 
> First - When both displays are (actually) enabled, in Display Configuration
> - can you confirm which display you have set to be primary?
> 
> Second - can you run the following in a terminal and paste the output into a
> reply in this report?
> 
> kscreen-doctor -o
> 
> Thanks again.

Hi,
when both displays are enabled I set the monitor (connected to the display port) as primary and the LG TV (connected to the HDMI port) as secondary.

# with only monitor primary enabled:

$ kscreen-doctor -o
Output: 1 HDMI-A-1
    disabled
    connected
    priority 0
    HDMI
    Modes:  1:1920x1080@60*!  2:1920x1080@60  3:1920x1080@60  4:1920x1080@50  5:1920x1080@30  6:1920x1080@30  7:1920x1080@25  8:1920x1080@24  9:1920x1080@24  10:1280x1024@60  11:1360x768@60  12:1152x864@60  13:1280x720@60  14:1280x720@60  15:1280x720@60  16:1280x720@50  17:1024x768@60  18:800x600@60  19:720x576@50  20:720x480@60  21:720x480@60  22:720x480@60  23:720x480@60  24:640x480@60  25:640x480@60  26:640x480@60  27:720x400@70 
    Geometry: 0,0 1920x1080
    Scale: 1
    Rotation: 1
    Overscan: 0
    Vrr: incapable
    RgbRange: Automatic
    HDR: disabled
    Wide Color Gamut: disabled
    ICC profile: none
    Color profile source: sRGB
    Color power preference: prefer efficiency and performance
    Brightness control: supported, set to 100% and dimming to 100%
Output: 2 DP-1
    enabled
    connected
    priority 1
    DisplayPort
    Modes:  28:1920x1080@60*!  29:1920x1080@60  30:1920x1080@60  31:1920x1080@50  32:1680x1050@60  33:1280x1024@75  34:1280x1024@60  35:1440x900@60  36:1280x960@60  37:1280x720@60  38:1280x720@60  39:1280x720@60  40:1280x720@50  41:1024x768@75  42:1024x768@70  43:1024x768@60  44:832x624@75  45:800x600@75  46:800x600@72  47:800x600@60  48:800x600@56  49:720x576@50  50:720x576@50  51:720x576@50  52:720x480@60  53:720x480@60  54:720x480@60  55:720x480@60  56:720x480@60  57:640x480@75  58:640x480@73  59:640x480@67  60:640x480@60  61:640x480@60  62:640x480@60  63:720x400@70 
    Geometry: 0,0 1920x1080
    Scale: 1
    Rotation: 1
    Overscan: 0
    Vrr: incapable
    RgbRange: Automatic
    HDR: incapable
    Wide Color Gamut: incapable
    ICC profile: none
    Color profile source: sRGB
    Color power preference: prefer efficiency and performance
    Brightness control: supported, set to 55% and dimming to 100%

# with enabled monitors and TV:

$  kscreen-doctor -o
Output: 1 HDMI-A-1
    enabled
    connected
    priority 2
    HDMI
    Modes:  1:1920x1080@60*!  2:1920x1080@60  3:1920x1080@60  4:1920x1080@50  5:1920x1080@30  6:1920x1080@30  7:1920x1080@25  8:1920x1080@24  9:1920x1080@24  10:1280x1024@60  11:1360x768@60  12:1152x864@60  13:1280x720@60  14:1280x720@60  15:1280x720@60  16:1280x720@50  17:1024x768@60  18:800x600@60  19:720x576@50  20:720x480@60  21:720x480@60  22:720x480@60  23:720x480@60  24:640x480@60  25:640x480@60  26:640x480@60  27:720x400@70 
    Geometry: 0,0 1920x1080
    Scale: 1
    Rotation: 1
    Overscan: 0
    Vrr: incapable
    RgbRange: Automatic
    HDR: disabled
    Wide Color Gamut: disabled
    ICC profile: none
    Color profile source: sRGB
    Color power preference: prefer efficiency and performance
    Brightness control: supported, set to 100% and dimming to 100%
Output: 2 DP-1
    enabled
    connected
    priority 1
    DisplayPort
    Modes:  28:1920x1080@60*!  29:1920x1080@60  30:1920x1080@60  31:1920x1080@50  32:1680x1050@60  33:1280x1024@75  34:1280x1024@60  35:1440x900@60  36:1280x960@60  37:1280x720@60  38:1280x720@60  39:1280x720@60  40:1280x720@50  41:1024x768@75  42:1024x768@70  43:1024x768@60  44:832x624@75  45:800x600@75  46:800x600@72  47:800x600@60  48:800x600@56  49:720x576@50  50:720x576@50  51:720x576@50  52:720x480@60  53:720x480@60  54:720x480@60  55:720x480@60  56:720x480@60  57:640x480@75  58:640x480@73  59:640x480@67  60:640x480@60  61:640x480@60  62:640x480@60  63:720x400@70 
    Geometry: 1920,0 1920x1080
    Scale: 1
    Rotation: 1
    Overscan: 0
    Vrr: incapable
    RgbRange: Automatic
    HDR: incapable
    Wide Color Gamut: incapable
    ICC profile: none
    Color profile source: sRGB
    Color power preference: prefer efficiency and performance
    Brightness control: supported, set to 55% and dimming to 100%

# in both cases the output of xrand does not change:

$ xrandr
Screen 0: minimum 16 x 16, current 1920 x 1080, maximum 32767 x 32767
DP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 476mm x 268mm
   1920x1080     59.96*+
   ...
HDMI-A-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 1600mm x 900mm
   1920x1080     59.96*+
   ...

When both monitors are enabled:
- If I click "Extend to the Right" from Display Configuration, even though the main monitor remains primary, it actually becomes secondary, and the mouse moves over the left edge of the TV (and not to the right as it should).
- Furthermore, to return to the primary monitor from Display Configuration, I have to click "Switch to External Monitor" (first icon), otherwise, if I click "Switch to Laptop Screen" (second icon), the signal goes to the TV, even if it's off. To go back, I either turn on the TV and switch from there, or I have to use the META+F1 macro to call Display Configuration and blindly move around with the keyboard to restore (because even if I reboot, this setting remains and there's no way to undo it).
It would be helpful to be able to assign shortcuts to the Display Settings icons; it would make things easier.
Comment 4 antonio 2025-07-21 20:02:45 UTC 
Created attachment 183405 [details]
display configuration with active monitor and TV
Comment 5 TraceyC 2025-07-22 16:49:27 UTC 
Thanks for the information. I'll let the kwin developers take a look from here.
Comment 6 Zamundaaa 2025-09-17 18:37:45 UTC 
Please attach the output of drm_info when the TV is off but still detected.

Almost certainly this is a case of "displays are terrible" though, TVs basically never tell the sources about being turned off. If you completely cut the power from the TV, the system should notice it disconnecting.
Comment 7 Bug Janitor Service 2025-10-02 03:46:28 UTC 
🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!
Comment 8 antonio 2025-10-02 13:34:24 UTC 
Created attachment 185454 [details]
drm_info output

I have attached the output of drm_info when the problem occurs.
Comment 9 TraceyC 2025-10-02 17:29:15 UTC 
Thanks