Have not looked deeply into the code, but I know it is important to work with the "DRM MODIFIERS" in order to work with a native (efficient) framebuffer format for the GPU (usually hardware custom tiling).

The hard part is to "blit" from a well-known framebuffer format to that native framebuffer format.

If I recall properly, on AMD GPU, you would use a 'DMA engine' which will perform the conversion (it may be obsolete and you may have to use the full GPU pipeline with texture image formats).

I dunno how much hardware abstraction there is in libdrm (and this is my own dawn fault as I should have dug deeper a long time ago in libdrm interface), do we have to "know" how to deal with the native format, or is there some (expensive) hardware abstraction to deal with this conversion?