Two displays one screen

Help
1

I have HP Envy 34 All-in-One https://www.hp.com/us-en/shop/mdp/desktops/hp-envy-34-all-in-one
It uses two displays in single monitor device. Plasma can’t use it as single device but Windows (and Gnome!) can.

Arch, latest plasma release (6.3.2), wayland.

PXL_20250303_155112196
PXL_20250303_1551121961920×1080 151 KB

PXL_20250303_155125709
PXL_20250303_1551257091920×1080 85.5 KB

PXL_20250303_155129737
PXL_20250303_1551297371920×1080 89.3 KB

PXL_20250303_155139264
PXL_20250303_1551392641920×1080 120 KB

2

What do kscreen-doctor -o and drm_info -j command output ?

sudo get-edid | parse-edid would be interesting too.

3 
[umnik@bigPC ~]$ kscreen-doctor -o
Output: 1 DP-1
        enabled
        connected
        priority 1
        DisplayPort
        Modes:  1:2560x2160@60*! 
        Geometry: 0,0 2560x2160
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: Automatic
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: EDID
        Color power preference: prefer accuracy
        Brightness control: supported, set to 100% and dimming to 100%
Output: 2 DP-2
        enabled
        connected
        priority 2
        DisplayPort
        Modes:  2:2560x2160@60*  3:2560x2160@60! 
        Geometry: 2560,0 2560x2160
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: Automatic
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: EDID
        Color power preference: prefer efficiency and performance
        Brightness control: supported, set to 100% and dimming to 100%

This is read-edid version 3.0.2. Prepare for some fun.
Attempting to use i2c interface
No EDID on bus 0
No EDID on bus 1
No EDID on bus 2
No EDID on bus 3
No EDID on bus 4
No EDID on bus 5
No EDID on bus 6
No EDID on bus 7
No EDID on bus 8
No EDID on bus 9
No EDID on bus 12
No EDID on bus 13
No EDID on bus 14
No EDID on bus 15
2 potential busses found: 10 11
Will scan through until the first EDID is found.
Pass a bus number as an option to this program to go only for that one.
256-byte EDID successfully retrieved from i2c bus 10
Looks like i2c was successful. Have a good day.
Checksum Correct

Section "Monitor"
        Identifier "HP ALL-in-One\"
        ModelName "HP ALL-in-One\"
        VendorName "HPN"
        # Monitor Manufactured week 0 of 2021
        # EDID version 1.4
        # Digital Display
        DisplaySize 800 340
        Gamma 2.20
        Option "DPMS" "false"

        #Extension block found. Parsing...
I only know about extension blocks of type 02h. PLEASE email me!
Something strange happened. Please contact the author,
Matthew Kern at <pyrophobicman@gmail.com>
4

File is too big for sending as reply: cloud.myachin.xyz/s/eR4Hs9SwL6yWQ2C

5

Displays like that are unfortunately not properly supported yet, see 427545 – Dual DisplayPort monitors (tiled, MST, e.g. 5k) are not supported by KWin

6

Any plans of fixing this on next iterations? I’d love to have kde on my all in one 5k desktop but this issue keeps me from using it :frowning:

Thank you

7

Yes, I’m mostly just missing testers at this point: https://invent.kde.org/plasma/kwin/-/merge_requests/1174

8

Count me in, I’m interested. I’m a bit of a Linux noob but quite eager to help with this matter.

9

I run Gentoo. If I knew how to make my own patches I’d love to test this out.. I have a LG 5k monitor and have been waiting a very long time for tiled/MST support in KDE!

10

How do I go about and help with testing? I’m a complete nab but with some simple guidance I can get there. I’ve got Ubuntu 25.10 and fedora kde 43.

Thank you

11

If you have some storage space and either decent compute power and/or plenty of time, the best way to test changes in core Plasma components is generally a development session with kde-builder: Set up a development environment | Developer

As long as the code doesn’t diverge too much from the 6.6 branch, I can also provide a patch on top of 6.6, if that’s easier to test.

12

Is the patch only meant for tiled displays, or is it possible to use any 2 monitors for that purpose?

If it’s the latter, I can help out with testing, as I not only have 2 monitors but also have stake in using 2 monitors as one (multimonitor gaming).

13

It’s only for actual tiled displays, the ability to combine normal displays is a bit different and will need to be added on top later.

14

I’d really like to test this patch, but I have no idea how to set this up in Gentoo (ironic I know) and it seems like a steep learning curve to do the development environment.

Once it hits 6.7, I’ll be happy to report any bugs I find though! Fingers crossed.