Libinput Working On User-Space Support For High Resolution Scroll Wheels
Red Hat's input expert, Peter Hutterer, has been working on the libinput patches for supporting high resolution scrolling support with what's needed by user-space. This feature is about allowing more precise scroll wheel support and should yield much smoother scrolling for devices like the Logitech Performance MX and others.
Of the user-space support, Peter has posted the latest patches. He commented about the work, "I tried integrating this into the xf86-input-libinput driver and it was...tricky. That driver needs to know everyhing ahead of time but with the current API you don't know the full click angle until you get the first discrete event. AFAICT, both mutter and weston would have similar issues when adding the above...There shouldn't be any need for wayland protocol updates either, we can just do the fraction of the movement so instead of 10 per event, we now send 10/120 * v120 value. So we need the compositors to handle a new API, but at least the wayland client side doesn't change."
Presumably this work will be squared away ahead of the next libinput release so once paired with Linux 5.0+ will allow for a smooth scrolling experience, assuming your Wayland compositor as well is updated for the new API.