Correct. All you have to do is start up mmiotrace, load nouveau, and then echo
nop > /sys/.../current_tracer (I forget the exact file, but it's on that wiki
page). And I wouldn't worry about that trailing Generally. I just look at the
page to remember what I have to echo into what files.

Note that mmiotrace has to be started *before* nouveau is loaded, so make sure
that it's (a) a module and (b) blacklisted from loading on startup. And it goes
without saying, but the HDMI device with audio support needs to be plugged in
while you're doing this.