Touchpad and Trackpoint on ThinkPad T480s

[Pali Rohár]

Hi!

I was trying to configure T480s's touchpad and trackpoint with xorg
libinput driver, but seems it is impossible to make it working properly.

Devices on ThinkPad T480s are identified as:

  ETPS/2 Elantech Touchpad
  ETPS/2 Elantech TrackPoint

Between touchpad and upper hw buttons is missing empty space. Therefore
if I press button in most cases I tap also on touchpad area which makes
double clicks. Scrolling via trackpoint + middle button is difficult too
as in this case I tap touchpad area too. Also speed of touchpad is not
perfect.

So for using touchpad it is needed to make some upper area of touchpad
be ignored. But I have not been able to do it with libinput xorg driver,
just with synaptics (option AreaTopEdge).

Here is my /etc/X11/xorg.conf.d/60-touchpad.conf which makes touchpad
usable:

Section "InputClass"
	Identifier	"Touchpad"
	MatchIsTouchpad	"True"
	MatchDevicePath	"/dev/input/event*"
	MatchProduct	"ETPS/2 Elantech Touchpad"
	Driver		"synaptics"
	Option		"GrabEventDevice"	"False"
	Option		"HorizEdgeScroll"	"True"
	Option		"HorizTwoFingerScroll"	"True"
	Option		"AdaptiveDeceleration"	"4.0"
	Option		"TapButton1"		"1"
	Option		"AreaTopEdge"		"150"
EndSection

Trackstick on T480s with libinput is I would say "slow". And whatever I
tried I was not able to make it "usable" for me with libinput. Therefore
I switched back to evdev input driver and after playing with
configuration options, I was able to make it usable for my work. For
reference here is my /etc/X11/xorg.conf.d/60-trackpoint.conf xorg
configuration:

Section "InputClass"
	Identifier	"Trackpoint"
	MatchIsPointer	"True"
	MatchDevicePath	"/dev/input/event*"
	MatchProduct	"ETPS/2 Elantech TrackPoint"
	Driver		"evdev"
	Option		"EmulateWheel"			"True"
	Option		"EmulateWheelButton"		"2"
	Option		"AccelerationTreshhold"		"2"
	Option		"AccelerationNumerator"		"10"
	Option		"AccelerationDenominator"	"5"
	Option		"ConstantDeceleration"		"0.7"
EndSection

Just to note that KDE on startup reset Acceleration* options, so they
needs to be set again with xinput at runtime:
xinput set-ptr-feedback 'ETPS/2 Elantech TrackPoint' 2 10 5

On ther other hand, older ThinkPad X1 3rd gen with synaptics touchpad
and IBM trackstick is working fine with libinput without any special
configuration.

So... do you have any idea how to configure libinput for ThinkPad T480s
to work like with above synaptics/evdev settings? I hope that libinput
would be more configurable or starts supporting these devices
out-of-box. Otherwise we would be needed to stick with synaptocs/evdev
drivers which do not have good defaults, but are configurable.

-- 
Pali Rohár
pali.rohar at gmail.com