Default Hysteresis causes poor, sticky and jumpy movement

[Trent Lloyd]

I have a Logitech T650 touch-pad. Out of the box, this device feels very poor to use because the HorizHysteresis and VertHysteresis settings are quite high. It is very difficult to make small movements, and if you want to move slightly diagonally it is basically impossible. The amount of movement on screen that it jumps is several mm on a 27" 1080p monitor.

It's hard to explain how horrible this is to use, but I would consider this "high" on the poor usability factor, not just a minor annoyance.

This setting causes movement to be ignored until it reaches the threshold.. it defaults to 0.5% of the hardwares diagonal size or about "14". This is designed to reduce noise on some devices, but I suspect the main issue here is that this is quite a large trackpad that is also very accurate. The hardware area is 2606x2110 which seems to be at least double most laptop trackpads.

Further testing on similar devices would be required, but this default algorithm may need some tweaking for device size and to scale better.. but obviously it is hard to know how this will affect other devices. Otherwise is there some way to build up a hardware quirks list? Probably not ideal but better than nothing.

The following significantly improves the feel:
synclient HorizHysteresis=0 VertHysteresis=0

As a side note, the scroll speed is also quite slow which again I suspect is related to the device being larger than many touch pads. VertScrollDelta and HorizScrollDelta of -65 work much better than the default -78 (or +78 for non-natural scrolling)

Neither of these settings can be configured in settings.

[Trent Lloyd (lathiat)]

Tested on xenial

[Trent Lloyd (lathiat)]

Looks like this was changed upstream in the libinput version to default to 0:
https://bugs.freedesktop.org/show_bug.cgi?id=93503

This will affect most touchpads so we should consider changing it

[Trent Lloyd (lathiat)]

See also https://bugs.freedesktop.org/show_bug.cgi?id=93846

[penalvch (penalvch)]

Trent Lloyd, thank you for reporting this and helping make Ubuntu better.

Could you please run the following command once from a terminal by ensuring you have the package xdiagnose installed, and that you click the Yes button for attaching additional debugging information:
apport-collect 1553061

When reporting xorg related bugs in the future, please do so via the above method. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.