[SOLVED] Kde Wayland wrong resolution external monitor

nasko · 2024-04-23 22:28:36

I'm using a Lenovo Thinkpad E15 with two external DELL monitors, 1920x1200 each.

Ever since I switched to Wayland about a week ago, I started experiencing this problem and it's really driving me nuts - every once in a while, after a reboot one of the monitors' resolution would be detected as 1920x1080 with a max refresh rate of 30 Hz instead of 60 Hz.
And this is only after KDE plasma starts - while on the SDDM login screen the monitor is running properly in 1920x1200 @ 60Hz. Right after I login and Plasma starts, the monitor is detected as 1920x1080. I can tell that the monitor is working fine before SDDM login, because when I activate the monitor menu from its panel, it shows the current resolution as 1920x1200. After Plasma starts, when I activate the same menu, it reports current resolution is 1920x1080 @ 30Hz with a maximun resolution of 1920x1200.

I tried this sequence of actions:

- I deleted the ~/.local/share/kscreen folder
- Reinstalled kscreen to no avail - the monitor is still detected wrong and I can no longer find newly generated config files, in fact I can't find a kscreen folder in ~/.local/share/ anymore.
- Restarted
- Ran Display Configuration in System Settings - the problematic monitor was shown as 1920x1080, but the Resoluiton drop-down had another value: 1920x1200. However, the Refresh Rate drop-down had a max value of 30 Hz. When I select the proper resolution 1920x1200 and click on the Apply button, the monitors flickered, then the Resolution drop-down once again shows 1920x1080 with the max resolution value missing from the available options.

- Output of lspci -k | grep -A 2 -E "(VGA|3D)"
- Output of kscreen-console config
- Output of kscreen-console output

The monitor in question is listed in the third section: Device ID: "xrandr-Dell Inc.-DELL U2415-7MT017CL1FMU"

What looks suspicious to me is taht its type is reported as "DisplayPort", while the second external monitor is reported correctly as: "HDMI".
Since this is a laptop, they're both connected to HDMI ports.

This issue is only manifested with Wayland - as soon as I restart in X11, both monitors are properly detected and functioning properly.

I was once able to get the monitor to be detected properly by swapping the HDMI cable with a high-end, more expensive one, as I suspected a low quality cable might be the curplit. But this didn't last long - a full day worth of uptime, including 2 or 3 restarts. Then after the 4th restart, the issue was manifested again.

I'd be thankful for any hints that might help me resolve this.

KDE Plasma Version: 6.0.4
KDE Framework Version: 6.1.0
Qt Version: 6.7.0
Kernel Version: 6.8.7-arch1-1 (64-bit)
Graphics adapter: Intel Corporation Alder Lake-UP3 GT2 [Iris Xe Graphics] (rev 0c)
Graphics Processor: Mesa Intel Graphics

Last edited by nasko (2024-04-25 13:19:51)

nasko · 2024-04-24 07:57:59

nasko wrote:

I was once able to get the monitor to be detected properly by swapping the HDMI cable with a high-end, more expensive one, as I suspected a low quality cable might be the curplit

After the problem resurfaced again even with the new cable, I tried multiple restarts and HDMI cable unplugs/plugs I figured a way to make it work almost everytime, which makes me think it was not the quality of the cable that fixed it the first time around. When the problem is manifested:

- I'd unlug the relevant HDMI cable
- Restart the computer
- Plug the HDMI cable
- Open Display Configuration and set the mode of the problematic monitor to 1920x1200 @ 60
- Click on the Apply button

Now in one out of two cases the proper resolution would hold after the display flickering and I would then click on the Keep button to confirm the changed configuration. In those cases when after the display flickers I'd still see the wrong resolution of 1920x1080, I'd repeat the unplug-restart-plug routine and after the next restart I'd be able to set the proper resolution.

nasko · 2024-04-24 08:10:05

I'm using a Dlink DUB-M520 docking station

Dlink DUB-M520 docking station

While plugging/uplugging the HDMI cable it feels really hot, so it could be that this docking station is causing the issue, although this doesn't explain why the monitor is detected properly as 1920x1200 in X11 and before SDDM login.

seth · 2024-04-24 12:37:32

Does it hinge on the panel or the output?
ie. if you swap the ports where the monitors are attached, does the other monitor now have the problem or does it stay with the currently affected one?
(I did see that they're the same model)

Also, when the symptom manifests, please post

for OUT in /sys/class/drm/card*; do echo $OUT; edid-decode $OUT/edid; echo "================="; done

You'll need https://aur.archlinux.org/packages/edid-decode-git

nasko · 2024-04-24 12:47:10

seth wrote:

Does it hinge on the panel or the output?
ie. if you swap the ports where the monitors are attached, does the other monitor now have the problem or does it stay with the currently affected one?

Looks like it's bound to the port - the monitor that's plugged into the dock station's HDMI manifests the issue.

seth wrote:

Also, when the symptom manifests, please post
for OUT in /sys/class/drm/card*; do echo $OUT; edid-decode $OUT/edid; echo "================="; done
You'll need https://aur.archlinux.org/packages/edid-decode-git

Sure, will post that once it happens. It's a working day for me so I don't want to deliberately go there :-)

Thanks!

seth · 2024-04-24 13:08:04

I missed post #3 (still had the tab open from the morning) - it's *very* likely the adapter (dock)

Edit: does it matter which USB port you use for the dock?

Last edited by seth (2024-04-24 13:10:56)

nasko · 2024-04-24 13:16:52

seth wrote:

does it matter which USB port you use for the dock?

Unfortunately this model laptop only has one combined Charging/DisplayPort Alt USB Type-C port, so there's nowhere else to plug the dock.

Anyways, I've had enough of this budget half-@ss excuse of a dock, so I just ordered the ThinkPad Universal USB-C Dock (40AY) and it's arriving tomorrow. Hopefully I'll never experience this issue once I swap docks.

nasko · 2024-04-25 13:26:01

Marking this thread as solved, as after swapping the D-Link dock for a ThinkPad Universal USB-C Dock, I did a bunch of restarts and the display resolution issue did not manifest.
I'm only sorry for not having done this earlier.

Thanks @seth and everyone else who took their time to read through my issue!

Arch Linux

#1 2024-04-23 22:28:36

[SOLVED] Kde Wayland wrong resolution external monitor

#2 2024-04-24 07:57:59

Re: [SOLVED] Kde Wayland wrong resolution external monitor

#3 2024-04-24 08:10:05

Re: [SOLVED] Kde Wayland wrong resolution external monitor

#4 2024-04-24 12:37:32

Re: [SOLVED] Kde Wayland wrong resolution external monitor

#5 2024-04-24 12:47:10

Re: [SOLVED] Kde Wayland wrong resolution external monitor

#6 2024-04-24 13:08:04

Re: [SOLVED] Kde Wayland wrong resolution external monitor

#7 2024-04-24 13:16:52

Re: [SOLVED] Kde Wayland wrong resolution external monitor

#8 2024-04-25 13:26:01

Re: [SOLVED] Kde Wayland wrong resolution external monitor

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