Public bug reported:

[Impact]

 * Touchpad using libinput behaves badly. It's imprecise for small
movements, the cursor jumps from one point to another, movements seem to
take a while to register, etc., specially if compared to the Synaptics
driver that was used in Xenial. Since users will upgrade from Xenial to
Bionic, this can be regarded as a regression.

 * A regression that can make several touchpads behave very, very badly,
is not something to be desired. Even more for a LTS release that'll be
the "flagship" for new users for a whole 2 years.

 * The only working solution is reverting back to the Synaptics driver.

 * libinput 1.11 (and 1.11.1) fixes this. In this release, Peter
Hutterer analysed the acceleration code from macOS and Windows and was
able to replicate it in libinput. I've tested it in Fedora, upgrading
from 1.10.5 to 1.11 and the difference is simply massive. No more missed
clicks, no more imprecise movements. It behaves like in macOS.

 * On top of that, numerous bugs here in launchpad related to hysteresis
and sensitivity and problems with specific models will be fixed as a
consequence, too.


[Test Case]

 * Get a laptop with a touchpad

 * Install Ubuntu 16.04.4, which uses the Synaptics driver, or Windows,
or macOS. Make some small movements.

 * Now install Ubuntu 18.04, which uses libinput. Check that the
touchpad is much less responsive, or sometimes even unusable due to how
it behaves in small movements. Use it for an extended period of time.

 * This issue is specially pronounced in Elantech touchpads, in my
experience.


[Regression Potential] 

 * Like any big upgrade, this can bring some problems. It seems there
weren't any major ones, judging by other distros' bug trackers, as well
as libinput's official bug tracker.

 * It should spend a lot of time in proposed or be considered for
backporting only, and we should allow users to test it a lot, if
possible.

 * libinput 1.11.1 has a bug
(https://gitlab.freedesktop.org/libinput/libinput/issues/50) that can
make some touchpads not appear in the device listing. Maybe we should
wait for libinput 1.11.2, or use the code as of this commit:
https://gitlab.freedesktop.org/libinput/libinput/commit/7c51c881dc72827ca50ae9eea3d123eef9cb4a66


[Other Info]
 
 * Users who do report problems are a minority. Even then, there are several 
instances of users complaining about these issues in the forums and AskUbuntu.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: libinput10 1.10.4-1
ProcVersionSignature: Ubuntu 4.15.0-23.25-generic 4.15.18
Uname: Linux 4.15.0-23-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
BootLog: Error: [Errno 13] Permissão negada: '/var/log/boot.log'
CompositorRunning: None
CurrentDesktop: KDE
Date: Thu Jun 21 10:47:22 2018
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
DkmsStatus: nvidia, 390.48, 4.15.0-23-generic, x86_64: installed
GraphicsCard:
 Intel Corporation HD Graphics 620 [8086:5916] (rev 02) (prog-if 00 [VGA 
controller])
   Subsystem: Dell HD Graphics 620 [1028:0781]
   Subsystem: Dell GM108M [GeForce 940MX] [1028:0781]
InstallationDate: Installed on 2018-06-21 (0 days ago)
InstallationMedia: Kubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 004: ID 0cf3:e007 Atheros Communications, Inc. 
 Bus 001 Device 003: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card 
Reader Controller
 Bus 001 Device 002: ID 0bda:5769 Realtek Semiconductor Corp. 
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. Inspiron 7460
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-23-generic 
root=/dev/mapper/kubuntu--vg-root ro quiet splash nouveau.runpm=0 vt.handoff=1
SourcePackage: libinput
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/31/2018
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.5.4
dmi.board.name: 0V736W
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias: 
dmi:bvnDellInc.:bvr1.5.4:bd01/31/2018:svnDellInc.:pnInspiron7460:pvr:rvnDellInc.:rn0V736W:rvrA01:cvnDellInc.:ct10:cvr:
dmi.product.family: Inspiron
dmi.product.name: Inspiron 7460
dmi.sys.vendor: Dell Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.91-2
version.libgl1-mesa-dri: libgl1-mesa-dri 18.1.1-0~b~padoka0
version.libgl1-mesa-glx: libgl1-mesa-glx 18.1.1-0~b~padoka0
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.0.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 
2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2

** Affects: libinput (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug bionic ubuntu

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https://bugs.launchpad.net/bugs/1778072

Title:
  [SRU or Backport][Bionic] Touchpad is imprecise for small movements,
  keeps missing clicks, the cursor jumps after being stopped for a
  while. Upgrade to libinput 1.11 fixes it.

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