[SOLVED] HDMI Audio not working Wandboard Quad Rev. C1

[enzeneer]

First of all, a big thank you for making the image available for the Wandboard. I was able to get a minimal X install with Chromium browser working in no time. I am using a standard HDMI 1920x1080 monitor and had to make zero configuration changes to get the display working. The problem is that there is no audio output from the HDMI. Infact the snd_hda_codec_hdmi module is not loaded at all.
$this->bbcode_second_pass_code('', '
# lsmod | grep '^snd' | column -t
snd_soc_fsl_ssi 12082 2
snd_soc_sgtl5000 13746 2
snd_soc_fsl_spdif 10521 2
snd_soc_imx_spdif 2149 0
snd_soc_imx_sgtl5000 3804 0
snd_soc_core 168837 8 imx_pcm_dma,imx_pcm_fiq,snd_soc_sgtl5000,snd_soc_imx_sgtl5000,snd_soc_imx_spdif,snd_soc_fsl_ssi,snd_soc_fsl_spdif
snd_compress 8351 1 snd_soc_core
snd_soc_imx_audmux 5652 1 snd_soc_imx_sgtl5000
snd_pcm_dmaengine 5734 1 snd_soc_core
snd_pcm 94969 5 imx_pcm_fiq,snd_soc_core,snd_soc_sgtl5000,snd_soc_fsl_ssi,snd_pcm_dmaengine
snd_timer 21233 1 snd_pcm
')

So the sound hardware is not detected :
$this->bbcode_second_pass_code('', '
# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: imxspdif [imx-spdif], device 0: S/PDIF PCM snd-soc-dummy-dai-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: imx6wandboardsg [imx6-wandboard-sgtl5000], device 0: HiFi sgtl5000-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0
')

Even though the HDMI is active:
$this->bbcode_second_pass_code('', '
# cat /sys/class/drm/card0-HDMI-A-1/status
connected
')

Note that there is no sound output from other devices too. I checked that those are activated using alsamixer.

Any ideas what could be wrong?

[enzeneer]

for posterity: the key is to use the linux-wandboard kernel rather than the mainline linux-armv7 kernel. Using the wandboard kernel immediately detects the HDMI audio port.