[Sound-open-firmware] HDMI audio not working on Up^2

[Pierre-Louis Bossart]

> I tried to test HDMI audio on Up^2 and hdac_hdmi_set_hw_params() is
> failing with -ENODEV because no port is assigned. Some very light
> analysis and debugging showed, that hdac_hdmi_pcm_open() hasn't
> been called, but it might wrong. Are there any non-trivial
> requirements to use HDMI audio on Up^2? Can it be, that my monitor
> or my cable aren't good enough?

You need to set the PortN-PinM mixers, otherwise the hw_params will 
fail. It's super painful and I don't know why it's needed but that's 
what it is for now.
I typically look for the dmesg, find out which port is not disconnected, 
and usually set Port6Pin0 to 1, then use hw:0,1 to get things to play.
I don't have the hardware with me so can't provide better advice.
Also please use the dapm graph tool to make use everything is setup 
correctly.