It is a bit of a pain. I am working on fixing it all.
apt-get install linux-backports-modules-alsa-`uname -r`
This will get them listed (aplay -l | grep -i 'hdmi')
You will likely have hw0 devices 3,7,8, and 9. It is almost always 3 or 7 on the id41, and seems to be completely random which. Others output on 9... others output on everything. Should look something like:
card 0: NVidia [HDA NVidia], device 3: NVIDIA HDMI [NVIDIA HDMI]You can test with:
card 0: NVidia [HDA NVidia], device 7: NVIDIA HDMI [NVIDIA HDMI]
card 0: NVidia [HDA NVidia], device 8: NVIDIA HDMI [NVIDIA HDMI]
card 0: NVidia [HDA NVidia], device 9: NVIDIA HDMI [NVIDIA HDMI]
speaker-test -c 2 -l 1 -t sine -D hw:0,7etc based on the output of aplay where the 0 is the card and 7 is the device.
Now getting that to stick is another trick. In /usr/pluto/templates/asound.conf I would replace %MAIN_CARD% with 0,7 or whatever yours is.
You may also have to add
options snd-hda-intel model=auto or
options snd-hda-intel enable_msi=0 index=-2
to /etc/modprobe.d/alsa-base.conf to place the HDMI audo as card 0. For reasons I do not understand, it has to be card 0.
Please report back with your results.