Dell Latitude 7480 press shift keys triggers random mouseclick when `Tap to click` enabled on touchpad.

Bug #1754052 reported by Peter Karlsson on 2018-03-07
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux (Ubuntu)

Bug Description

In Ubuntu 16.04.3 and 17.10.1 holding down either shift key on a Dell Latitude 7480 causes random mouse clicks to occur without being nowhere near the touchpad with palms. No external mouse/keyboard connected. Disabling `Tap to click` in `Mouse & Touchpad` settings makes the problem go away. The problem is not present in 14.04.5, whether installed or live CD.

How to reproduce:

1. On a Dell Latitude 7480 live boot (or install) one of the following images:
- ubuntu-16.04.3-desktop-amd64.iso
- ubuntu-17.10.1-desktop-amd64.iso

2. Open `Mouse & Touchpad` and make sure `Tap to click` is enabled.
3. Click `Test Your Settings` and make sure window has focus.
4. Hold down either shift key and after a few seconds single/double clicks start registering.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xorg 1:7.7+13ubuntu3
ProcVersionSignature: Ubuntu 4.10.0-28.32~16.04.2-generic 4.10.17
Uname: Linux 4.10.0-28-generic x86_64

ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
CasperVersion: 1.376.2
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Wed Mar 7 13:00:21 2018
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
 Intel Corporation Device [8086:5916] (rev 02) (prog-if 00 [VGA controller])
   Subsystem: Dell Device [1028:07a0]
LiveMediaBuild: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
MachineType: Dell Inc. Latitude 7480
 PATH=(custom, no user)
ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/username.seed boot=casper quiet splash ---
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install) 01/30/2018
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.8.2 00F6D3
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.8.2:bd01/30/2018:svnDellInc.:pnLatitude7480:pvr:rvnDellInc.:rn00F6D3:rvrA00:cvnDellInc.:ct10:cvr: Latitude 7480
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.76-1~ubuntu16.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 17.0.7-0ubuntu0.16.04.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 17.0.7-0ubuntu0.16.04.1
version.xserver-xorg-core: xserver-xorg-core N/A
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A

Peter Karlsson (peterkarlsson) wrote :
Timo Aaltonen (tjaalton) on 2018-03-07
affects: xorg (Ubuntu) → linux (Ubuntu)

This change was made by a bot.

Changed in linux (Ubuntu):
status: New → Confirmed
Joseph Salisbury (jsalisbury) wrote :

Did this issue start happening after an update/upgrade? Was there a prior kernel version where you were not having this particular problem?

Would it be possible for you to test the latest upstream kernel? Refer to . Please test the latest v4.16 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.


Changed in linux (Ubuntu):
importance: Undecided → Medium
status: Confirmed → Incomplete
Peter Karlsson (peterkarlsson) wrote :

I have tested upstream kernel v4.16-rc4 and can confirm the problem persists. However I managed to borrow another Latitude E7440 and for the time I had access to that laptop I could not reproduce the problem. Therefore I have to conclude that it is a hardware problem, not a software one.

Peter Karlsson (peterkarlsson) wrote :

Hardware related

Changed in linux (Ubuntu):
status: Incomplete → Invalid
To post a comment you must log in.
This report contains Public information  Edit
Everyone can see this information.

Other bug subscribers