Comment # 29 on bug 1013647 from Martin Wilck

The POINTINGSTICK_CONST_ACCEL trick ceased to work with libinput 1.9.

See https://bugs.freedesktop.org/show_bug.cgi?id=106323 for technical
background. Once this bug is solved, there'll probably be a better solution for
recent libinput versions, too. 


Update on possible workarounds, other than falling back from the ALPS driver to
the generic PS/2 driver:

Solution 1: Use evdev

Under X, use the evdev input driver, and set the ConstantDeceleration property
to 8 or more.

  # cat >/etc/X11/xorg.conf.d/60-alps.conf <<EOF
  Section "InputClass"
      Identifier  "DualPoint Stick"
      MatchIsPointer  "true"
      MatchProduct    "DualPoint Stick"
      MatchDevicePath "/dev/input/event*"
      Driver  "evdev"  
      Option  "AccelerationProfile" "2"
      Option  "ConstantDeceleration" "8"
  EndSection
  EOF

Solution 2: libinput < 1.9

With libinput < 1.9 (SLE12, Leap 42.x): set POINTINGSTICK_CONST_ACCEL to a low
value:

# cat >/etc/udev/rules.d/80-libinput.rules <<EOF
ACTION=="add|change", KERNEL=="event[0-9]*", ENV{ID_INPUT_POINTINGSTICK}=="?*",
\
     ENV{POINTINGSTICK_CONST_ACCEL}="0.1"
EOF

Solution 3: libinput >= 1.9

With libinput 1.9 and higher (SLE15, Tumbleweed), set
LIBINPUT_ATTR_TRACKPOINT_RANGE to the maximum value 100:

# cat >/etc/udev/rules.d/80-libinput.rules <<EOF
ACTION=="add|change", KERNEL=="event[0-9]*", ENV{ID_INPUT_POINTINGSTICK}=="?*",
\
     ENV{LIBINPUT_ATTR_TRACKPOINT_RANGE}="100"
EOF

Furthermore, set the acceleration profile in libinput to "flat" and the
acceleration factor to a low value such as -0.9, using xinput commands.

Note: The results of this are much worse than using evdev, see above.