HDMI RGB communitation

Hello,
I’m trying to just tryout display with ILI9806E without too much experience around linux drivers so i wanted to just connect it on parallel 16bit rgb bus while HDMI is active and be “snoofing” that communication with that display.

I forced proper resolution and CVT with reduced blanking initialized and properly set that display but without good results.
Display is showing some mess which is reacting to changes in framebuffer:

My question is, if it is even compatible or does hdmi IO using totally some different protocol then standard parallel rgb?

Is there some other way how to easily force linux to output data on that bus? I’m initializing lcd from user-space by spi, all i need is just some regular 16bit data on rgb bus.