[kde] [Bug 507151] New: confusion between primary and secondary screen

[antonio]

https://bugs.kde.org/show_bug.cgi?id=507151

            Bug ID: 507151
           Summary: confusion between primary and secondary screen
    Classification: I don't know
           Product: kde
      Version First unspecified
       Reported In:
          Platform: Debian unstable
                OS: Linux
            Status: REPORTED
          Severity: normal
          Priority: NOR
         Component: general
          Assignee: unassigned-bugs at kde.org
          Reporter: antdev66 at gmail.com
  Target Milestone: ---

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

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