Reworked Touchpad Acceleration For Libinput: No Longer Terrible
The Red Hat input developer explained, "This patchset is a cleanup and revamp of the touchpad acceleration code. It doesn't give us perfect acceleration, but it goes from the current rather abysimal state to one that should at least be good enough most of the time...he first 10 patches separate the touchpad code from the mouse acceleration code and switch it to use mm/s as base velocity unit (rather than the current 1000dpi-mouse-equivalency units). 11 is the main change that changes the acceleration pattern, mostly to start accelerating at a lot higher finger speed (found mostly by trial and error)."
Those details via this patch series while Peter Hutterer also wrote a blog post with much more information about these touchpad acceleration improvements. He concluded over there in that interesting post for those curious about the technical side of input, "what this means is that the new code accelerates later but when it does accelerate, it goes faster. I tested this on a T440s, a T450p and an Asus VivoBook with an Elantech touchpad (which is almost unusable with current libinput). They don't quite feel the same yet and I'm not happy with the actual acceleration, but for 90% of 'normal' movements the touchpad now behaves very well. So at least we go from "this is terrible" to "this needs tweaking". I'll go check if there's any champagne left."
Libinput is now used by many Linux distributions as the universal input handling library used by not only Wayland systems but also X11 via xf86-input-libinput and these days with Mir too.