The solution: add `i8042.nopnp` to the kernel command line. To do this:
sudoedit /etc/default/grub
and add:
GRUB_CMDLINE_LINUX="i8042.nopnp"
If there's already a line with `GRUB_CMDLINE_LINUX=…`, add `i8042.nopnp` inside the quotes, separated from any other word within the quotes by a space, e.g.
GRUB_CMDLINE_LINUX="some-other=option i8042.nopnp"
Then run
sudo update-grub
and reboot. Hope it works, it worked for me!