Bug#950981: touchpad stopped working reliably

[Michael Biebl <biebl@debian.org>]

Package: libinput10
Version: 1.15.1-1
Severity: important

Hi Timo,

I encounter a very nasty regression with the latest update of libinput.
The touchpad in my X220 no longer works reliably.
When I swipe over the touchpad area, sometimes the cursor simply stops
moving. This happens sporadically.
Downgrading to 1.14.3-1 fixes the issue immediately.

libinput list-devices output (removed a few unrelated entries)

Device:           SynPS/2 Synaptics TouchPad
Kernel:           /dev/input/event5
Group:            8
Seat:             seat0, default
Size:             74x43mm
Capabilities:     pointer gesture
Tap-to-click:     disabled
Tap-and-drag:     enabled
Tap drag lock:    disabled
Left-handed:      disabled
Nat.scrolling:    disabled
Middle emulation: disabled
Calibration:      n/a
Scroll methods:   *two-finger edge
Click methods:    *button-areas clickfinger
Disable-w-typing: enabled
Accel profiles:   none
Rotation:         n/a

Device:           TPPS/2 IBM TrackPoint
Kernel:           /dev/input/event6
Group:            9
Seat:             seat0, default
Capabilities:     pointer
Tap-to-click:     n/a
Tap-and-drag:     n/a
Tap drag lock:    n/a
Left-handed:      disabled
Nat.scrolling:    disabled
Middle emulation: disabled
Calibration:      n/a
Scroll methods:   *button
Click methods:    none
Disable-w-typing: n/a
Accel profiles:   flat *adaptive
Rotation:         n/a

Device:           ThinkPad Extra Buttons
Kernel:           /dev/input/event7
Group:            10
Seat:             seat0, default
Capabilities:     keyboard switch
Tap-to-click:     n/a
Tap-and-drag:     n/a
Tap drag lock:    n/a
Left-handed:      n/a
Nat.scrolling:    n/a
Middle emulation: n/a
Calibration:      n/a
Scroll methods:   none
Click methods:    none
Disable-w-typing: n/a
Accel profiles:   n/a
Rotation:         n/a

(This output from libinput 1.14.3)


-- System Information:
Debian Release: bullseye/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.4.0-3-amd64 (SMP w/4 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8), LANGUAGE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libinput10 depends on:
ii  libc6         2.29-10
ii  libevdev2     1.8.0+dfsg-2
hi  libinput-bin  1.14.3-1
ii  libmtdev1     1.1.5-1.1
ii  libudev1      244.2-1
ii  libwacom2     1.1-2

libinput10 recommends no packages.

libinput10 suggests no packages.

-- no debconf information