Bug 464459

Summary:	Input-settings in xorg .conf files ignored by Plasma on X11
Product:	[Applications] systemsettings	Reporter:	Matthias Mueller <mat.mueller>
Component:	kcm_mouse	Assignee:	Plasma Bugs List <plasma-bugs>
Status:	RESOLVED INTENTIONAL
Severity:	normal	CC:	kde, nate
Priority:	NOR
Version:	5.26.5
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Matthias Mueller 2023-01-18 14:09:10 UTC

SUMMARY
I've tried setting a different mouse sensitivity for the touchpad (is treated as a mouse though) on my wireless couch-keyboard. Works like a charm with "xinput set-prop", but won't work when put into a xorg .conf file.
In the xorg-log, it seems to be applied, but when doing a 'xinput list-props xx", it is back to the old value.
When trying "startx /usr/bin/xterm", it gets applied properly and is correctly listed in list-props.

So it seems that plasma is doing something that overwrites these settings after they are applied by X11.

Options that are affected from my experiments are at least "AccelProfile" and "AccelSpeed", i haven't really tested other ones though.
I guess the options are applied according to what is set in the mouse section of system settings - in there, there is no possibility to set separate values for different mice though.

It seems there are a few other inactive bugreports that share the same origin:
https://bugs.kde.org/show_bug.cgi?id=435247
https://bugs.kde.org/show_bug.cgi?id=357194
https://bugs.kde.org/show_bug.cgi?id=339743

STEPS TO REPRODUCE
1. create .conf file in "/etc/X11/xorg.conf.d"

2. Specify InputClass with AccelSpeed Option - my example:
Section "InputClass"
Identifier "touchpad-sens"
MatchDriver "libinput"
MatchIsPointer "true"
MatchProduct "2.4G Receiver"
Option "AccelProfile" "flat"
Option "AccelSpeed" "0.3"
EndSection

3. Reboot and see options not applied properly although reported as set in xorg log

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Archlinux Kernel 6.1.6
KDE Plasma Version: 5.26.5
KDE Frameworks Version: 5.102.0
Qt Version: 5.15.8

ADDITIONAL INFORMATION
Don't know if it matters, but i use SDDM and X11 session, haven't tried on plasma-wayland yet though.
Also, i'm not sure if this is a plasmashell but or maybe kwin?

Comment 1 Nate Graham 2023-01-18 20:29:59 UTC

Why can't you use the mouse settings page in System Settings, out of curiosity? Does it not offer the settings you need?

Comment 2 Matthias Mueller 2023-01-18 23:00:46 UTC

(In reply to Nate Graham from comment #1)
> Does it not offer the settings you need?

I guess you could say so, yes. ^^
Changing the mouse-settings in ksystemsettings affects all attached mice equally/offers no option to change them individually.
Maybe i should have clarified that i want to change the sensitivity of the couch-keyboard only, while leaving the sens of the desktop mouse as is - sorry for that confusion.

Comment 3 Nate Graham 2023-01-20 23:27:29 UTC

You can do that too; mouse settings are per-mouse--at least on Wayland. I can't remember if they're per-mouse on X11 too.

Comment 4 Matthias Mueller 2023-01-21 10:07:39 UTC

I knew i should have checked on wayland, too! It's not possible on X11 though.

Well, if it is already implemented in wayland i guess the main question is how much effort it would be to port it over (i don't know how similar the codepaths for wayland and X11 are in that regard?).
If it's a lot of work and already implemented in the futureproof version, i'd almost say it's too much of a niche usecase to put too much effort into it, isn't it?

Comment 5 Nate Graham 2023-01-23 20:08:05 UTC

I would be inclined to say the same thing, yeah. Thanks for understanding!