psm0: unable to allocate IRQ

I've spent the last 2 days attempting to get a fresh install of
stable/13-n252407-f42139db639 working on a Dell Inspiron 5755.
The problem I struggled with was getting the trackpad (synaptics?)
to be recognized and function. As it is, it's only ever recognized
as a mouse, and then, only if i kldload(8) ums(4). I'm pretty
sure this is on a psm(4). But any attempts to use psm fail with
psm0: unable to allocate IRQ.
An error I found in dmesg(8) on a verbose boot. Anybody familiar
with this, or have any thoughts on how I might track this down?

To rule out hardware; I installed Slackware along side the
FreeBSD install, and it has no trouble creating a full featured
trackpad under the MATE DE.

Thank you for all your time, and consideration.

--chris