The substance of this question is in the title and in bold. Some touchpads, designed for Win8/10, behave erratically with the Linux
i2c-hid kernel module.
There are a lot of questions related to Elantech touchpads not working. This question is not a duplicate. Well, it is, but it isn't. Basically, these touchpads are super finicky and have given a lot of people problems under a variety of conditions.
Sometimes it works or doesn't work when I reboot and the mouse cursor does or doesn't appear. Sometimes it stops working when I'm typing on page 37 of a particular document in Abiword, but page 23 when using LibreOffice. Sometimes it becomes extra finicky when using even-numbered kernel updates, but super stable with odd-numbered updates. Same for any Ubuntu releases ending in .04 or .10 ... or that occur on a prime-numbered year, or when the sum of the digits of the version number is prime (1+8+0+4 = 13). Often it stops working when it "knows" I'm doing something important, exactly 666 ms before I am about to save my work.
In short, all of these details are just random noise. They have nothing to do with whether the touchpad works. It is just a horrible device designed to make my life miserable. But I can't tear my laptop apart to replace it!
This is a meta-question intended to get at the underlying problem with these touchpads, which is they are all on laptops that ran Windows 8/10.
Is there is no ritual, no magic, that can make this touchpad cooperate with operating systems christened outside the MS Temple? What praises can I utter? What blessings can I seek? To make this touchpad work?