[Wayland-bugs] [Bug 96848] Slow and fast movements on T450s touchpad are unpredictable

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=96848

Peter Hutterer <peter.hutterer at who-t.net> changed:

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--- Comment #1 from Peter Hutterer <peter.hutterer at who-t.net> ---
there's two components that matter: libinput touchpad acceleration is different
to the synaptics one (depending on the hardware, because the synaptics one
doesn't take hw into account so it varies greatly, libinput is mostly the same
on all touchpads). libinput is slower than synaptics by default and it is more
tied to your fingers, i.e. once you stop moving it stops quicker than
synaptics. this (theoretically) allows for more precise positioning since the
cursor stops with your finger and you shouldn't overshoot too much.

as for small movements: the T450 has broken hardware. if you move slowly from
left to right you see that the motion is not continuous but rather comes in
waves. this is a hw issue, the sensors are too far apart (or the firmware
filters it) and we don't get motion events in the gaps between. we work around
this in libinput and avoid pointer jumps but there's only so much we can do,
you still get the wavy motion. See Bug 94379 for more info.

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