Bug 406099

Seems a bit like Bug 400173.

Is this still happening in Plasma 5.22, by any chance?

Still happens occasionally - generally with a kernel upgrade. One kernel will be fine, the next might have problems, then clean for 4-5 kernel updates before it gives out again.

Huh, thanks.

It sounds like this is actually a kernel issue, and while GNOME may be more resilient against it (good!), ideally it would be fixed in the kernel.

The next time it happens, can you paste the output of `kscreen-doctor-o`? Thanks

Such timing:

~]$ kscreen-doctor --outputs
Output: 445 DVI-I-0 enabled connected  DVI Modes: 446:1280x1024@60! 447:1280x1024@75* 448:1152x864@75 449:1024x768@75 450:1024x768@70 451:1024x768@60 452:800x600@75 453:800x600@72 454:800x600@60 455:800x600@56 456:640x480@75 457:640x480@73 458:640x480@60 Geometry: 1920,28 1280x1024 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: unknown 
Output: 459 DVI-I-1 disabled disconnected  DVI Modes: Geometry: 0,0 0x0 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: unknown 
Output: 460 HDMI-0 disabled disconnected  HDMI Modes: Geometry: 0,0 0x0 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: unknown 
Output: 461 DP-0 disabled disconnected  DisplayPort Modes: Geometry: 0,0 0x0 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: unknown 
Output: 462 DP-1 disabled disconnected  DisplayPort Modes: Geometry: 0,0 0x0 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: unknown 
Output: 463 DVI-D-0 enabled connected primary DVI Modes: 446:1280x1024@60 448:1152x864@75 450:1024x768@70 451:1024x768@60 454:800x600@60 455:800x600@56 458:640x480@60 464:1920x1080@60*! 465:1440x900@60 466:1280x800@60 Geometry: 0,0 1920x1080 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: unknown primary


It's been interesting - this was an issue in F34 but not in F35, then resurfaced with F36.

Thanks. And which port is the non-functional monitor plugged into? Which port is the working monitor plugged into?

The non-functioning monitor is plugged into the first port. On boot up the system reads this as the primary monitor. Within Fedora I have this set as the secondary monitor. It's an older VGA monitor.

The working monitor is plugged into the second port. On boot the system reads this as an "extra" monitor. Within the OS this is set to the primary monitor. This is a somewhat newer DVI monitor.

I'd thought they had different connectors on the video board but in looking at it just now, they both have DVI connections on the board.

So they are both plugged into DVI ports on your graphics card?

And if you manually enable the disabled monitor on the Display Configuration page, it gets disabled again later?

Both are plugged into DVI ports.

On boot: The monitor that normally displays the login screen is blank. Almost as if not receiving any data but, if I hit return and enter my password, login continues and both monitors display the startup screens. Then the images for the two monitors change over to their "correct in KDE" locations. When looking at the Display Configuration the VGA monitor shows enabled as the secondary monitor and the DVI monitor shows as the primary.

Okay, now if you reboot again, do both monitors get enabled *after login* as expected, or does one of them fail to display again?

The next reboot everything works as it's supposed to. 

So: apply patches, reboot, login screen is invisible. Login blind, both screens appear in KDE. Reboot again, login screen is visible again.

Continues to work properly through several patches, then the login screen goes invisible. Usually this happens after a new kernel is applied. The most recent one was not associated with a kernel update. There were 5 or so library (I think) updates.

Thanks for all the info. Here's what I think is happening:

1. For some reason, the monitor in question does not get enabled by default. If you manually enable it, it works.
2. Sometimes, kernel upgrades cause the monitor's EDID, serial number, or connected port name to change, so KScreen inappropriately detects it as a new screen, which triggers the original bug of it not being enabled by default all over again.

The first issue is probably more easily fixable so let's use this bug report to track it. The second issue is much more challenging to fix in KScreen, but we're working on it for Plasma 5.27.

What Plasma version are you using now?

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
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tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

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If you have already provided the requested information, please
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current Plasma version is 5.26.3

Are you using an NVIDIA GPU, by any chance?

yes
nvidia-gpu-firmware v. 20221109 release 144.fc36
kmod-nvidia-6.0.8-200.fc36.x86_64 kernels

Aha!

*** This bug has been marked as a duplicate of bug 460341 ***