Bug 465742

Summary:	Hi-res scroll stopped working in 5.27
Product:	[Plasma] kwin	Reporter:	[object Object] <rohan>
Component:	input	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED NOT A BUG
Severity:	normal	CC:	xaver.hugl
Priority:	NOR
Version First Reported In:	5.27.0
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description [object Object] 2023-02-15 03:54:35 UTC

SUMMARY
Hi-res scrolling seems to not work at all (have tried QT apps, Firefox, and GTK apps)

STEPS TO REPRODUCE
Try to scroll with a hi-res mouse on 5.27.0

OBSERVED RESULT
Apps scroll with low res (like how it was before hi-res scroll was implemented on wayland)

EXPECTED RESULT
Hi-res scrolling

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch
(available in About System)
KDE Plasma Version: 5.27.0
KDE Frameworks Version: 5.103.0
Qt Version: 5.15.8

Comment 1 Zamundaaa 2023-02-15 09:28:41 UTC

Can you run
> sudo libinput debug-events
and check if the kernel still uses high resolution scrolling? For some mice it was disabled again.

Comment 2 [object Object] 2023-02-15 16:12:44 UTC

(In reply to Zamundaaa from comment #1)
> Can you run
> > sudo libinput debug-events
> and check if the kernel still uses high resolution scrolling? For some mice
> it was disabled again.

Yeah that's one of the first things I tried, forgot to put it in the issue, sorry
Libinput is getting hi-res scroll events, I'm also using logiops to manually make my logitech mouse use hi-res scroll so it would be kind of weird if it stopping working anyway

Comment 3 [object Object] 2023-02-15 17:09:03 UTC

https://invent.kde.org/plasma/kwin/-/commit/9f494da9fa29fd2a8abd34e5bde95d531026301e

Maybe it could be this commit?

Comment 4 [object Object] 2023-02-15 17:10:38 UTC

Also, it did work on 5.26.90 so the regression occurred after that

Comment 5 Vlad Zahorodnii 2023-02-17 10:13:08 UTC

(In reply to [object Object] from comment #4)
> Also, it did work on 5.26.90 so the regression occurred after that

high resolution scrolling requires both compositor _and_ client support. Most native wayland clients in the wild don't support wl_pointer.axis_value120, so kwin sends lores scrolling to keep the compatibility.

This requires toolkit changes. Not sure about GTK but Qt should support high resolution scrolling on wayland in 6.5 https://codereview.qt-project.org/c/qt/qtwayland/+/439967

Comment 6 [object Object] 2023-02-17 15:49:05 UTC

(In reply to Vlad Zahorodnii from comment #5)
> (In reply to [object Object] from comment #4)
> > Also, it did work on 5.26.90 so the regression occurred after that
> 
> high resolution scrolling requires both compositor _and_ client support.
> Most native wayland clients in the wild don't support
> wl_pointer.axis_value120, so kwin sends lores scrolling to keep the
> compatibility.
> 
> This requires toolkit changes. Not sure about GTK but Qt should support high
> resolution scrolling on wayland in 6.5
> https://codereview.qt-project.org/c/qt/qtwayland/+/439967

Then those clients include firefox and every qt/gtk app I've tried, effectively preventing me from using high-res scrolling at all. Having a couple clients scroll extremely fast seems like the better alternative to having high-res scroll disabled everywhere, imo the change should be reverted or there should be an option to turn it on/off then

Comment 7 [object Object] 2023-02-17 15:52:42 UTC

All the apps I have installed worked fine with hi-res scroll in 5.26.90, so the apps it doesn't work with are probably in a minority