In embedded SoCs the GPU is typically "render only", and display is handled by a different hardware block ("display engine" etc), and of course both CPU and GPU

In embedded SoCs the GPU is typically "render only", and display is handled by a different hardware block ("display engine" etc), and of course both CPU and GPU can write to it. Well that's even true in desktop GPUs but it's just tightly coupled there, both blocks are on the same PCIe device so the support is in one driver. From the iPhone 7 Linux port we know that Apple is nothing special in terms of this (they have framebuffer working there)