Ah indeed, mainlining is still an issue for u-boot and linux unfortunately. I’ll have to add that to my wishlist above.
This also reminds me of another todo item. I talked with Lucas Stach and they pointed out that they want to make it so that there is only a single device tree upstream that allows for both the internal display and hdmi instead of having two different DTs (only one of which is upstreamed) that the user can switch between. Lucas plans to drive the internal display by the eLCDIF controller always, instead of the DCSS. This means the GPU wastes a bit of memory bandwidth copying the final image, as the eLCDIF can not handle the GPU tiling format directly. However the eLCDIF has better power efficiency…