Bug 91196

Summary:	Using mouse wheel to scroll to one direction sometimes jumps a bit to the other direction
Product:	Wayland	Reporter:	Mateus Rodrigues Costa <mateusrodcosta>
Component:	libinput	Assignee:	Wayland bug list <wayland-bugs>
Status:	RESOLVED NOTABUG	QA Contact:
Severity:	normal
Priority:	medium	CC:	peter.hutterer
Version:	unspecified
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Attachments:	evemu-record output

Description Mateus Rodrigues Costa 2015-07-02 17:52:44 UTC

So I'm using a USB mouse and using its wheel to scroll.
The problems is that sometimes when scrolling in either direction it will sometimes jump back a bit to the other direction.

Here are two videos showing it:
Scrolling up but jumping down in Terminal: https://vid.me/MSyZ
Scrolling down but jumping up in Chrome: https://vid.me/V6ow

Arch Linux x86_64
libinput 0.18.0-1
xf86-input-libinput 0.11.0-2
Running on a Xorg Gnome session

I tested on a new user also running a Xorg Gnome session and it happened there too.

Comment 1 Peter Hutterer 2015-07-02 23:56:20 UTC

please run evemu-record against your device while scrolling and attach the output here. I want to rule out any hardware-issues.

Comment 2 Mateus Rodrigues Costa 2015-07-03 00:16:51 UTC

Created attachment 116900 [details]
evemu-record output

I scrolled the page two times: one time fast and the other slowly.

Comment 3 Peter Hutterer 2015-07-03 02:43:56 UTC

hmm, not sure what to do here, this appears to be a hardware issue. Look at the events (after a grep):

E: 4.503993 0002 0008 -001	# EV_REL / REL_WHEEL            -1
E: 4.535996 0002 0008 -001	# EV_REL / REL_WHEEL            -1
E: 4.551996 0002 0008 -001	# EV_REL / REL_WHEEL            -1
E: 4.567994 0002 0008 -001	# EV_REL / REL_WHEEL            -1
E: 4.583995 0002 0008 -001	# EV_REL / REL_WHEEL            -1
E: 4.607994 0002 0008 -001	# EV_REL / REL_WHEEL            -1
E: 4.888004 0002 0008 0001	# EV_REL / REL_WHEEL            1
E: 4.911997 0002 0008 -001	# EV_REL / REL_WHEEL            -1
E: 4.928007 0002 0008 0001	# EV_REL / REL_WHEEL            1
E: 4.943995 0002 0008 0001	# EV_REL / REL_WHEEL            1
E: 4.959997 0002 0008 -001	# EV_REL / REL_WHEEL            -1
E: 4.983997 0002 0008 -001	# EV_REL / REL_WHEEL            -1
...

the first number is the time in seconds since starting evemu. so you do really get wrong scroll events on that mouse at random intervals. the rest of the log shows the same issue. 

note that the events are as they come directly from the kernel, libinput or other pieces of the stack have no effect here. in fact, these are the same events that libinput would see.

there isn't much we can do here tbh, looks like the HW is broken. sorry.

Comment 4 Mateus Rodrigues Costa 2015-07-03 03:12:53 UTC

Yup, I can confirm it's a hardware problem. I tested another mouse in this machine and couldn't reproduce.
Tested the same fault mouse on a Windows machine and reproduced it there.

Still, thanks for taking your time to look into this issue!
I will get a new mouse as soon as I can.

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