[noggin]

3D is broken on HDMI 2.0 port. Intel hasn't fixed this yet so that's why you need HDMI 1.4 port if you want full 3D.

This is what the guys with OLED and all 4K passive glasses are saying that you can use HDMI 2.0 port set the resolution to 4K in Kodi and play 3D files in interlaced mode. 3D to 4K interlaced screen conversion is done in the computer and TV gets single 4K frames at 24 fps. No further processing or 3D mode in the TV is not necessary as long at the screen is mapped 1 to 1 pixel.

Yep - it's not really interlaced, it's more interleaved. Rather than alternate lines being from two different points in time, it's alternate lines for each eye-view. This works because, whether the TV is in 3D mode or not, the permanent alternate-line polarisation used in passive 3D displays is always present. As long as you can ensure that alternate eye-views go to alternate 2160p lines and there is a 1:1 mapping, you should get 3D when you put on your glasses.

What Kodi would need to implement is a 3D playback mode that takes the MVC decoded video and scales each eye to 3840x1080, and then maps all the odd lines in the 2160p frame to lines from one eye, and all the even lines in the 2160p frame to lines from the other eye. How easy this is to do with shaders etc.? I have no idea!

HOWEVER - because the TV is not in a 3D mode internally, any TV on-screen graphics will be unaware of the 3D nature of the display. Probably not a major issue.

This technique would only work for UHD Passive displays though - not active.