Audio problem with Intel HDMI/DP

[Free BSD]

System Settings correctly identifies all three channels, .i.e, Rear stereo,
Front stereo, and HDMI/DP 8ch.
When I try any of the 3 Test buttons, it claims:

Error trying to play a test sound.

The system said: "No such driver"

dmesg shows three pcm devices:

dmesg|grep pcm
pcm0: <Realtek ALC671 (Rear Analog)> at nid 20 and 27 on hdaa0
pcm1: <Realtek ALC671 (Analog)> at nid 33 and 24 on hdaa0
pcm2: <Intel Kaby Lake (HDMI/DP 8ch)> at nid 3 on hdaa1

None of the rudimentary steps in handbook Sound chapter work, i.e., beep -d
/dev/dsp2.0, etc.

What driver does KDE believe is missing? This is a fresh install, installed
software from packages, but switched to ports trying to find audio
solutions.

I put hw.snd.default_unit=2 in /boot/loader.conf Still no sound from hdmi.
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