[Linaro-mm-sig] Split GEM from the rest of DRM

[Bridgman, John]

>> And, at least in our case, the driver for display controller may be
present, but sgx kernel module may not.  To make things look "normal"
to userspace, I've taken the approach of writing a DRM driver that
handles the KMS stuff, and has a plug-in API[1] that other drivers,
such as sgx, can register their own ioctl's and that sort of thing..
there are a few rough edges to sort out to make more than a single
plugin practical, but perhaps with an approach like this the vendor
could implement a platform specific DRM driver to handle the mode
setting and display bits, while ARM, IMG, etc (IP vendor) could each
use a standard plugin interface to write their own drivers to work
with the vendor provided display driver.

I remember Dave Airlie proposed something that sounded similar for the upstream DRM, with options for display, graphics and compute, so maybe this is something that could fit upstream fairly easily ?