alternate finger tapping causes cursor to jump

Bug #1284318 reported by chrispb on 2014-02-24
14
This bug affects 2 people
Affects Status Importance Assigned to Milestone
xserver-xorg-input-synaptics (Ubuntu)
Undecided
Unassigned

Bug Description

I've found that if I quickly alternate tapping with two fingers on the touchpad the cursor jumps wildly.

This is quite frustrating for me as I often move the cursor with one finger on my right hand while subsequently clicking the bottom left of the touchpad with the left to cause a 'left click' action. Often this causes my mouse to jump to the bottom left of the screen and open the cinnamon menu window.

It seems if I monitor events with xinput that the a[0] and a[1] events are being swapped.

motion a[0]=4734
motion a[0]=4734
motion a[0]=4733
motion a[1]=1984
motion a[1]=1983
motion a[1]=1982
motion a[1]=1980
motion a[1]=1983
motion a[1]=1987
motion a[1]=1991
motion a[1]=1996
motion a[1]=2001
motion a[0]=2760 a[1]=4719 <-- Jump happens here

...
Example 2:
motion a[0]=4578
motion a[0]=4578
motion a[0]=4577
motion a[0]=4577
motion a[0]=4576
motion a[0]=4575
motion a[0]=4575
motion a[1]=1990
motion a[1]=1989
motion a[1]=1987
motion a[1]=1986
motion a[1]=1984
motion a[1]=1983
motion a[0]=4577 a[1]=1977
motion a[0]=1472 a[1]=4719 <-- Jump happens here
motion a[0]=1472 a[1]=4722

I would have thought that the synaptics driver code would have identified 'erratic' input events which appear to be too far apart to be naturally occurring and simply filter them out?

I could not repeat this when I loaded an Ubuntu 13.10 Live USB disk but the Synaptics TouchPad driver did not appear to be loaded at that time as it didn't appear in xinput list.

 ~> lsb_release -rd
Description: Linux Mint 16 Petra
Release: 16

~>uname -a
Linux chris-XPS13 3.11.0-12-generic #19-Ubuntu SMP Wed Oct 9 16:20:46 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

~> dpkg -l | grep input-synaptics
ii xserver-xorg-input-synaptics 1.7.1-0ubuntu1 amd64 Synaptics TouchPad driver for X.Org server

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: xserver-xorg-input-synaptics 1.7.1-0ubuntu1 [modified: usr/share/X11/xorg.conf.d/50-synaptics.conf]
ProcVersionSignature: Ubuntu 3.11.0-12.19-generic 3.11.3
Uname: Linux 3.11.0-12-generic x86_64
ApportVersion: 2.12.5-0ubuntu2.2
Architecture: amd64
Date: Mon Feb 24 21:00:55 2014
InstallationDate: Installed on 2014-02-13 (11 days ago)
InstallationMedia: Linux Mint 16 "petra" - Release amd64 20131126
MarkForUpload: True
ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_GB.UTF-8
 SHELL=/usr/bin/fish
SourcePackage: xserver-xorg-input-synaptics
UpgradeStatus: No upgrade log present (probably fresh install)

chrispb (chris-p-bailey) wrote :
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in xserver-xorg-input-synaptics (Ubuntu):
status: New → Confirmed
Peter (puddingpete) wrote :

I am having the same problem.

I slide my mouse to something, then click my mouse button, but my mouse jumps across the screen before I get the click.

I'm confident there is a way to use synclient to ignore taps in the button area and hopefully mitigate the annoyance, but I haven't found it yet. Any temporary solutions?

Tobias Karlsson (karlsson-t) wrote :

I'm seing this behavior also and can repeat it easily. Worst part is that i have set AreaBottomEdge and if I tap quickly above AreaBottomEdge and then below (most often with my thumb to trigger a left click) cursor jumps to an edge This happens roughly every 10th left click. Is there anyone with an idea for a workaround? This issue is kind of a dealbreaker for me to use ubuntu. Seems silly to to have to use something as awful as windows just to get a working touchpad

chrispb, thank you for reporting this and helping make Ubuntu better.

As per https://wiki.ubuntu.com/Releases your release is EOL.

If you have an issue in a supported release (ex. 16.04) please file a new report, and feel free to subscribe me to it.

Changed in xserver-xorg-input-synaptics (Ubuntu):
status: Confirmed → Invalid
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