Hello,

I made some progress with the HDMI output on the board.

I updated to v4 of the exynos-simple-phy driver.
@Rahul: You can add a tested-by from me, if you want.

My dts now looks like this:
https://github.com/tobiasjakobi/linux-odroid/blob/odroid-3.15.y/arch/arm/boot/dts/exynos4412-odroidx2.dts

This works, but I have to force disabling of the LCD0 powerdomain:
https://github.com/tobiasjakobi/linux-odroid/commit/65b97415b90f54240e03a065cfea1097629fb17e

It looks like that the HDMI doesn't work properly when LCD0 pd is
switched off, which it normally is for my use case. The nodes related to
HDMI also don't seem to reference it. It seems like only the TV pd is
referenced, and from the looks of the kernel log this one gets
enabled/disabled properly.
@Inki: Is this a known problem?

Another issue which I then encountered can be easily triggered with
'modetest' from libdrm/tests:
modetest -M exynos -v -s 15@6:640x480

This triggers a kernel warning (mixer_dpms). I attached the full output.
Note that the warning appear when exiting modetest (so it's probably
triggeed by crtc restore or something).

With best wishes,
Tobias