I've captured some mmiotraces of the blob. There's a 26MB file at:
http://www.alloscomp.com/files/mmiotrace_minidp_hdmi.tar.bz2

To create these dumps, I:
    - closed X
    - disconnected my VGA monitor, leaving only the DP->HDMI monitor connected
    - rmmod nvidia
    - rmmod nouveau
    - enabled mmiotrace
    - modprobe (nvidia or nouveau, depending on the trace)
    - xinit "/bin/sleep 10"
    - disabled mmiotrace

To create the hotplug dump, I:
    - closed X (VGA monitor still connected)
    - rmmod nvidia
    - enabled mmiotrace
    - modprobe nvidia
    - xinit (to an xterm)
    - unplugged and replugged my DP monitor (with trace markers)
    - closed X
    - disabled mmiotrace