From what I can tell, and from what I have experienced, starting around kernel 4.12.x, multitouch gestures on some Thinkpads are messed up after the computer wakes from suspend. You can find some documentation of this on this Ubuntu bug report or, more relevantly, on this Arch forum post.
On my Thinkpad T440s (using KDE, though I don't think these issues are exclusive to KDE), I experienced two seemingly separate touchpad issues, one which began when I moved from kernel 4.9 to 4.14 (and which still persists on 4.18.5), and the other which showed up in January this year. I'm sharing the solutions to the two issues below.
You may only be experiencing one of these issues:
#1. Frozen touchpad after resuming suspend. Clicks don't work, mouse doesn't move.
#2. Multitouch gestures do not work after resuming from suspend. This could mean no two-finger scrolling, no two-finger right click, no ctrl+click, no scroll action on the right side of the touchpad, etc. You might experience one or all of these symptoms. For me, two-finger scrolling still worked, but all the other symptoms listed above were present.
Thinkpad T440s (my laptop), T440p, X-250, and others (check that ubuntu thread linked above).
#1. For the totally frozen mouse, I resolved this by updating the BIOS. @nadb helped me out with both of the issues in this post, and he suspected that the frozen mouse was related to the microcode updates for Spectre mitigation (and indeed, the timeline of when this started for me matches up perfectly with those Spectre patches).
Is your BIOS old? Check with
inxi -Fzxc0 and look for
UEFI [Legacy]: LENOVO v: GJET77WW (2.27 ) date: 05/20/2014
Cool - my BIOS was 4 years old!
You can update your BIOS easily by burning it to a DVD, and then booting from that DVD. It took me roughly 10 minutes to update, and it went smoothly.
https://pcsupport.lenovo.com/us/en/downloads/ds035967https://support.lenovo.com/us/en/downloads/ds035965burn it to dvd, make sure you are plugged in to a power source, do not interrupt and boot using the dvd.
After doing that, I was at
UEFI [Legacy]: LENOVO v: GJET99WW (2.49 ) date: 06/05/2018 and the frozen touchpad issue was resolved.
#2. For the nonfunctional multitouch gestures, the Arch forum linked above provides the answer.
add the following to /etc/modprobe.d/psmouse_serio2_setup.conf:
options psmouse synaptics_intertouch=0
Hopes this helps someone!