@liam, you missed my *edit below, I meant to say "all mobile gpu blobs". (post editing still broken in Opera)
Even if some SoC has a block for that, the binary drivers for that soc rarely support using it.
I take it that by "binary drivers" you mean just the gpu blob? If so, that may, or may not be true. It depends on whether the display is connected solely to the gpu. I don't know the answer.
I would ASSUME that the framebuffer is located on system memory and that it would have a path to the display. If so, I would agree that the gpublob needn't be aware of these other ASICs.
I define "mobile gpu binary blob" as everything the vendor ships as their "display drivers". I have used multiple vendors on ARM and no blob has any support for 2d accel (and the 3d drivers generally suck, too).