After a bit of a hiatus, I updated the UP Board to Kernel 4.11-rc8, and HDMI sound is now supported..

In the kernel config, under ‘ALSA for SoC audio support‘, select ‘X86 sound devices‘, and ‘HDMI audio without HDaudio on Intel Atom platforms‘

After (re)boot to 4.11-rc8:

[rgadsdon@rgup ~]$ ll /dev/snd
total 0
drwxr-xr-x 2 root root 60 Apr 24 22:18 by-path
crw-rw---- 1 root audio 116, 2 Apr 24 22:18 controlC0
crw-rw---- 1 root audio 116, 3 Apr 24 22:18 pcmC0D0p
crw-rw---- 1 root audio 116, 1 Apr 24 22:18 seq
crw-rw---- 1 root audio 116, 33 Apr 24 22:18 timer

My next ‘Intel’ project is a low-cost small laptop, based on a Chromebook, running Linux/Fedora25 natively, and more details will be coming soon..

Robert Gadsdon.   April 26, 2017..