Selecting memory manager for embedded DRM device

Hello,

I'm looking onto writing DRM/KMS drivers for few pieces of embedded equipment. I stumbled upon selecting GEM/TTM/whatever for them. Could you please guide me?

From my point of view, there are two major cases:

1) Device with embedded/separate VRAM.

2) Device using system memory w/o any restrictions.

Those are embedded devices hanging on memory bus, so no such things as AGP, aperture exist.

I'm looking for advice on selecting proper MM.