[Wayland/KDE] Virtual touchscreen doesn't work until associated with an output

[abdecd]

Is there an existing issue for this?

• I have searched the existing issues

Is your issue described in the documentation?

• I have read the documentation

Is your issue present in the latest beta/pre-release?

This issue is present in the latest pre-release

Describe the Bug

I encountered an issue where touchscreen input doesn't work correctly on KDE Wayland.

Steps to reproduce:

1. Start Sunshine on KDE Plasma Wayland.
2. Connect using an Android client with native touchscreen forwarding support (tested with https://github.com/Axixi2233/moonlight-android).
3. Switch to native Touch Mode.
4. Tap anywhere on the desktop.

The touch input does not work correctly.

After some debugging, I found a reproducible workaround and collected a few observations that may help narrow down the issue.

Observed behavior:

• While the touch input fails, KWin repeatedly logs:
  Could not find logical output for KWin::DrmOutput(...)
• evtest receives the expected touch events.
• libinput debug-events also reports correct touch events.

Findings:

The virtual touchscreen created by Sunshine (via Inputtino) has an empty outputName property in KWin's D-Bus interface.

When I manually assign the active output to the device through KWin's D-Bus API, touch input immediately starts working correctly and the KWin log messages stop.

I'm not sure whether this should ultimately be handled by Sunshine, Inputtino, or KWin, but I hope these findings help identify the appropriate component.

Expected Behavior

Touchscreen inputs should work.

Additional Context

As a temporary workaround, manually assigning the active output to the virtual touchscreen through KWin's D-Bus API immediately restores native touch input.

This bash script below worked for me:

#!/bin/bash
# Auto-detect active display
TARGET_OUTPUT=$(kscreen-doctor -j 2>/dev/null | jq -r '.outputs[] | select(.enabled == true) | .name' | head -n 1)
[ -z "$TARGET_OUTPUT" ] && exit 1

# Map Sunshine touch device to the display
for event in $(qdbus6 org.kde.KWin /org/kde/KWin/InputDevice org.kde.KWin.InputDeviceManager.ListTouch 2>/dev/null); do
    name=$(qdbus6 org.kde.KWin /org/kde/KWin/InputDevice/$event org.freedesktop.DBus.Properties.Get org.kde.KWin.InputDevice name 2>/dev/null)
    if [ "$name" = "Touch passthrough" ]; then
        qdbus6 org.kde.KWin /org/kde/KWin/InputDevice/$event org.freedesktop.DBus.Properties.Set org.kde.KWin.InputDevice outputName "$TARGET_OUTPUT"
    fi
done

Host Operating System

Linux

Operating System Version

Linux kernel: 7.1.2-3-cachyos, KDE Plasma: 6.7.2, Wayland

Architecture

amd64/x86_64

Package

Linux - AUR (Third Party)

GPU Type

NVIDIA

GPU Model

NVIDIA GeForce RTX 5060 Ti

GPU Driver/Mesa Version

595.71.05

Capture Method

None

Apps

Log output

Online logs

https://gist.github.com/abdecd/c829f40e216868d3c606af42993af386