We have a bunch of nVidia ION mini-PCs (Revo, ER-1401) in our Linux posse - and they were great when new - wipe Windows, install Linux, add nVidia drivers, adjust overscan on TV, sorted.
BUT - the nVidia driver utility no longer has an overscan slider in the GUI, and there are haughty statements on the nVidia site proclaiming this as better, since one can now fiddle with something like modelines until it works as intended.
Well, if I'm going to acquire hack-fu skills on their hardware, it's going to be on the open 'Nouveau' driver.
Long story short there is some xrandr-fu necessary to overcome before the cheap TVs we bought will display properly without overscan. This is not about that - it is about the next problem. No sound.
nVidia state clearly on their page
that Nouveau (and nv) do not support HDMI audio... They say this in section 5.
Well, they are wrong.
On the Nouveau site
there is a matrix that shows the NV-50 (ION GPU) is supported.
A bit of tinkering revealed that we needed to use Alsamixer to enable the SPDIF outputs (tab to SPDIF, then hit 'M' to toggle Mute Mode) and install Pavucontrol. Seems HDMI appears as SPDIF....
The Pulse Audio Volume control then lets one set the correct output Configuration (for us it was HDMI stereo out, analog input) and we were in business.
So, contrary to what nVidia say, HDMI sound does work with Nouveau!
Tested on REVO & ER1401 ION systems under Bodhi Linux 2 (Ubu 12.04 base)