dolphs it certainly doesn't work out-of-the-box. If pins are compatible (didn't check) you would need to modify DTB file to tell that spdif should be enabled. That would be ideally solved with DT overlays, but currently there is no support for that in AW images.
mike2002 There is certainly a difference in output. Interestingly, AVR adds some strange video modes like 1440x480@60Hz and 2880x480@60Hz. Can you edit "extlinux/extlinux.conf" on SD card and add drm.debug=0xe at the end of APPEND line? Please provide full dmesg output and output of cat /sys/kernel/debug/clk/clk_summary with AVR connected.
andre_276 while it's true that mainline kernel doesn't support HDMI audio on any of Allwinner SoC, images here contains support for up to 8 channels linear PCM HDMI audio. This is obviously work in progress, but eventually this work will be included in mainline kernel. You can dig out patches from LE build system if you are interested.