https://bugs.kde.org/show_bug.cgi?id=525409
Bug ID: 525409
Summary: Drawing tablet pen is always mapped to internal eDP
display; configured outputName is ignored.
Classification: Plasma
Product: kwin
Version First 6.7.4
Reported In:
Platform: Manjaro
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: multi-screen
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
**Summary**
[Wayland] Drawing tablet pen is always mapped to internal eDP display;
configured `outputName` is ignored
**Description**
On a multi-monitor Wayland setup, the pen of my Huion RDS-220 pen display is
always mapped to the laptop's internal eDP-1 display instead of the RDS-220
display.
KDE System Settings correctly shows the tablet as mapped to the RDS-220. KWin's
live D-Bus InputDevice object also reports `outputName = "DP-1"`, which is the
output connected to the RDS-220.
However, actual pen input is mapped to eDP-1.
The mapping onto eDP-1 itself appears geometrically correct: placing the pen at
the upper-left of the RDS-220 places the cursor at the upper-left of the laptop
display, etc. The problem appears specifically to be selection of the wrong
output.
Changing `outputName` live over KWin's D-Bus interface does not change the
actual output used by the pen.
**Hardware / display layout**
Tablet display:
* Huion RDS-220
* Input device: `Huion Tablet_RDS-220 Pen`
* USB ID: `256c:2001`
* libinput device: `/dev/input/event21`
* Physical tablet size reported by libinput: approximately 160x100 mm
Displays:
```
DP-1
UUID: 3d9f1755-41d8-4ee6-a811-3d3100a9c191
Geometry: 0,1440 2560x1440
Scale: 1
This is the Huion RDS-220.
HDMI-A-1
UUID: bb9c752f-3f08-4a26-a498-35bc60e15c14
Geometry: 0,0 2560x1440
Scale: 1
eDP-1
UUID: 0fb5e6d1-5a0b-425c-a27a-f43ed4b2e1ac
Geometry: 2560,0 2560x1440
Scale: 1
This is the laptop's internal display.
```
**Software**
* Manjaro Linux
* KDE Plasma 6.7.4
* KWin 6.7.4
* Wayland session
* libinput 1.31.3
**Steps to reproduce**
1. Connect the Huion RDS-220 in a three-monitor Wayland configuration as
described above.
2. Open System Settings -> Input & Output -> Drawing Tablet.
3. Select `Huion Tablet_RDS-220 Pen`.
4. Set "Map to screen" to RDS-220 / DP-1.
5. Move the pen over the RDS-220.
**Observed result**
The cursor appears and moves on the laptop's internal eDP-1 display.
The mapping onto eDP-1 is normalized correctly. For example, the upper-left of
the tablet maps to the upper-left of eDP-1 and the lower-right maps
correspondingly.
**Expected result**
The pen should be mapped to DP-1, the RDS-220 display selected in System
Settings.
**KWin configuration**
`~/.config/kcminputrc` contains:
```
[Libinput][9580][8193][Huion Tablet_RDS-220 Pen]
CalibrationMatrix=1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1
OutputArea=0,0,1,1.1
OutputUuid=3d9f1755-41d8-4ee6-a811-3d3100a9c191
```
The UUID is the correct UUID for DP-1.
**Live KWin InputDevice state**
Querying:
```
busctl --user introspect \
org.kde.KWin \
/org/kde/KWin/InputDevice/event21 \
org.kde.KWin.InputDevice
```
shows, among other properties:
```
calibrationMatrix = "1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1"
enabled = true
inputArea = 0 0 1 1
isVirtual = false
mapToWorkspace = false
name = "Huion Tablet_RDS-220 Pen"
outputArea = 0 0 1 1.1
outputName = "DP-1"
product = 8193
size = 159.839 99.8994
```
Thus KWin's live device object also reports the expected `outputName = "DP-1"`.
**Changing outputName at runtime**
I tested changing the live property directly:
```
busctl --user set-property \
org.kde.KWin \
/org/kde/KWin/InputDevice/event21 \
org.kde.KWin.InputDevice \
outputName s "HDMI-A-1"
```
Reading the property afterwards confirms:
```
s "HDMI-A-1"
```
However, the actual pen cursor remains mapped to eDP-1.
Changing it back to `DP-1` likewise changes the D-Bus property but not the
actual pen mapping.
I also tested:
```
mapToWorkspace = true
```
through the same D-Bus InputDevice interface. The property changes
successfully, but the pen remains mapped exclusively to eDP-1.
**Test with eDP-1 disabled**
I disabled the internal display with:
```
kscreen-doctor output.eDP-1.disable
```
while DP-1 and HDMI-A-1 remained active.
Pen input then produced no visible cursor/input on either remaining display. It
appears that KWin continued mapping the tablet into the now-disabled eDP-1
output rather than remapping it to DP-1.
Re-enabling eDP-1 restored the previous behavior.
**Raw libinput test**
The native pen produces sensible absolute coordinates through libinput:
```
sudo libinput debug-events --device /dev/input/event21
```
Example positions included approximately:
```
12.46 / 9.14
33.41 / 9.55
17.12 / 88.87
4.91 / 93.73
154.47 / 90.02
```
for a tablet reported as approximately 160x100 mm.
Thus the kernel/libinput input coordinates appear to traverse the tablet area
correctly.
**KWin device enumeration**
KWin sees only the expected native RDS-220 interfaces:
```
event21 "Huion Tablet_RDS-220 Pen"
event22 "Huion Tablet_RDS-220"
event23 "Huion Tablet_RDS-220 Keyboard"
```
There is no second native tablet pen object in KWin.
**Huion proprietary driver**
The Huion proprietary Linux driver (`huiontablet 15.0.0.162-1`) was initially
installed and running. It creates additional virtual Huion input devices.
For troubleshooting, the Huion software was completely exited. `ps` confirmed
that neither `huionCore` nor `huiontablet` was running, and `libinput
list-devices` then contained only the native RDS-220 interfaces listed above.
The problem described here occurs with the proprietary Huion software stopped
and the native `Huion Tablet_RDS-220 Pen` device handled by libinput/KWin.
**Additional observation**
With the proprietary Huion software stopped, KDE System Settings contains only
the native RDS-220 tablet rather than the additional virtual Huion devices.
System Settings reports that this native device is mapped to the RDS-220. This
agrees with both `kcminputrc` and KWin's live `outputName = "DP-1"` property,
but disagrees with actual behavior.
In short, the configuration appears correct at all inspected levels, but KWin
maps the tablet to eDP-1 regardless of the configured/live `outputName`.
My configuration:
Operating System: Manjaro Linux
KDE Plasma Version: 6.7.4
KDE Frameworks Version: 6.29.0
Qt Version: 6.11.2
Kernel Version: 7.1.13-2-MANJARO (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 9 5900HX with Radeon Graphics
Memory: 32 GiB of RAM (30,7 GiB usable)
Graphics Processor 1: AMD Radeon Graphics
Graphics Processor 2: AMD Radeon RX 6800M
Manufacturer: ASUSTeK COMPUTER INC.
Product Name: ROG Strix G513QY_G513QY
System Version: 1.0
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