Bug 57383

Summary:

Don't send motion events with no changes

Product:

xorg

Reporter:

Bastien Nocera <bugzilla>

Component:

Server/Input/Core

Assignee:

Peter Hutterer <peter.hutterer>

Status:

RESOLVED WONTFIX

QA Contact:

Xorg Project Team <xorg-team>

Severity:

normal

Priority:

medium

CC:

peter.hutterer

Version:

unspecified

Hardware:

Other

OS:

All

Whiteboard:

i915 platform:

i915 features:

Attachments:

Description	Flags
0001-dix-skip-subpixel-only-core-motion-events-57383.patch	none
foo	none

Description Bastien Nocera 2012-11-21 22:03:15 UTC

As filed originally in https://bugzilla.gnome.org/show_bug.cgi?id=688456

We receive motion events for a mouse sitting still on a Wacom tablet (in my case on an Intuos4 tablet).

Peter said:
> Server problem actually. Two reasons this can happen:
> 
> * devices with more than 2 axes may send events where only other axis values
> change, not x/y. the server doesn't filter those IIRC
> * devices with subpixel motion may move x/y but by less than a pixel and we
> still send core events for that even though they can't do subpixel.
> 
> Both of the above can be seen with the wacom tablets, the second one will be
> harder to ix than the first but pls file a bug regardless.
> 
> As for jitter: we have that in the drivers already, but you may still want to
> consider an application-specific jitter to guard against accidental bumps of
> the device in those apps where it makes sense.

Comment 1 Peter Hutterer 2012-12-18 06:59:09 UTC

Created attachment 71710 [details] [review]
0001-dix-skip-subpixel-only-core-motion-events-57383.patch

tentative patch, breaks three test cases here but I think this is a test case issue.

Comment 2 Bastien Nocera 2012-12-18 08:17:19 UTC

Much better, gets rid of some of the jitter, but it's not enough to fix some pretty bad problems:
- in some (physical) positions, the cursor will move between 2 very close locations. This will be visible on the screen, and causes gnome-terminal not to be able to hide the cursor for example.
- Some events are still delivered such that leaving the cursor within reach of the URL completion popup of the web browser will cause an unwanted item to be selected. Could still be a problem with the first item.

Comment 3 Peter Hutterer 2012-12-18 21:47:51 UTC

What physical device is this, and when/how does it occur? Does evtest show a fuzz for x/y on that device? does evtest show events when this occurs?

I have similar issues with one of the USB mice I have, but the movement is random, hardware-related and too high to filter it (tens of pixels).

Comment 4 Bastien Nocera 2012-12-18 23:00:39 UTC

Intuos 4 M with the 5-button mouse.

Comment 5 Peter Hutterer 2013-01-30 06:02:17 UTC

(In reply to comment #3)
> does evtest show events when this occurs?

Comment 6 Bastien Nocera 2013-03-13 13:53:37 UTC

Created attachment 76473 [details]
foo

This is the output of evtest dropping the mouse, and removing it from the tablet, without moving it.

Comment 7 Peter Hutterer 2013-03-26 00:15:37 UTC

Thanks. evtest shows a fuzz of 4 for the x/y axes. In the wacom driver we use a default of 2 atm, I'll look into updating the wacom driver to use the device-specific value.

However, the input data also shows that the actual input data is higher than the claimed fuzz (highest here appears to be 6 device units). So the problem would remain. I suggest using Option "Suppress" in a config snippet for the wacom device to avoid the jitter.

As long as the movement is across pixel boundaries, we cannot really discard them in the server since we have no heuristics to detect erratic movement vs real movement.

Comment 8 Peter Hutterer 2016-11-28 04:39:42 UTC

This is a mass change of bugs. Bugs assigned to me that haven't been updated in the last 3 years are closed as WONTFIX, because, well, let's at least be honest about it.

Please do not re-open unless you have a really good reason to do so (e.g. you're fixing it yourself). If it hasn't been fixed in the last 3 years, it probably won't be fixed anytime soon either. Sorry.

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