SUMMARY This is a small hobbyscreen I have. Libinput detects it just fine but it doesn't show up in the mouse, touchpad or touchscreen kcms. Using the screen doesn't control the mouse pointer. This might be a regression as I remember testing the screen a year or so back and it worked. I also tested with a Steam Deck and a Kodi HTPC and the touchscreen works fine with those $ sudo libinput list-devices Device: WaveShare WS170120 Kernel: /dev/input/event7 Id: usb:0eef:0005 Group: 4 Seat: seat0, default Capabilities: touch Tap-to-click: n/a Tap-and-drag: n/a Tap button map: n/a Tap drag lock: n/a Left-handed: n/a Nat.scrolling: n/a Middle emulation: n/a Calibration: identity matrix Scroll methods: none Scroll button: n/a Scroll button lock: n/a Click methods: none Clickfinger button map: n/a Disable-w-typing: n/a Disable-w-trackpointing: n/a Accel profiles: n/a Rotation: 0.0 Area rectangle: n/a SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 6.6.80 KDE Frameworks Version: 6.26.0 Qt Version: 6.11.0 Kernel Version: 6.19.14-arch1-1 (64-bit) Graphics Platform: Wayland Processors: 12 × AMD Ryzen 5 2600 Six-Core Processor Memory: 64 GiB of RAM (62.7 GiB usable) Graphics Processor: AMD Radeon RX 5700
If this is hardware-specific you'll have to debug this yourself I'm afraid
I think it might be because its a raw touch device without any pointer abstractions. My laptop trackpad for example reports: Capabilities: pointer gesture and my Steam Controller reports Capabilities: keyboard pointer
I did some digging: With a debug function in kwin/src/backends/libinput/device.cpp in Device::Device it turns out that the touchscreen never reaches it. Every other device passes m_touch and sets it to false, but the screen doesn't show up in the logs when plugging in.
Oh and the cursor is controller perfectly fine on the same computer when using kmscon.
I digged as far as I could and the problem seems to exist between libinput and kwin.
https://gitlab.freedesktop.org/libinput/libinput/-/work_items/1282
Shame. The bug report on libinput bugtracker was a dead end.
Some observations I maked in the libinput issue to test what works and what doesnt Same computer kmscon TTY: Works Same computer gamescope standalone session: Doesn't work Steam Deck: Works but input is rotated 90° Steam Deck desktop mode: Works but input is rotated 90° Proxmox server with Kodi on front: Works
Maybe also relevant for this bugreport: Looks as we had some bugs with the input matrix and they just got fixed. See https://bugs.kde.org/show_bug.cgi?id=521464
Thanks, I'll have a look when I get home this week.
I built master and ran the test environment. That did not fix the issue. The display still works fine in kmscon.
I did bisecting with kubuntu and the display stops working between 25.10 and 26.04 25.10: Plasma: 6.4.5 Frameworks: 6.17.10 Qt: 6.9.2 Libinput 1.28.1 26.04: Plasma: 6.6.4 Frameworks: 6.24.0 Qt: 6.10.2 Libinput: 1.13.1
CachyOS helped me hone it down even further 2026-03 release is working Plasma: 6.6.2 Frameworks: 6.23.0 Qt: 6.10.2 Kernel: 6.19.6 Libinput 1.30 2026-04 release not working Plasma: 6.6.4 Frameworks: 6.25.0 Qt: 6.11.0 Kernel: 6.19.10 Libinput 1.31.1
SYSTEMD AND UDEV ARE THE ISSUE!!!!! I downgraded to systemd 259.3-1 and the display works!
https://github.com/systemd/systemd/issues/43303
Nicely done!