drm/gem: Add drm_gem_object_funcs

This adds an optional function table on GEM objects.
The main benefit is for drivers that support more than one type of
memory (shmem,vram,cma) for their buffers depending on the hardware it
runs on. With the callbacks attached to the GEM object itself, it is
easier to have core helpers for the the various buffer types. The driver
only has to make the decision about buffer type on GEM object creation
and all other callbacks can be handled by the chosen helper.

drm_driver->gem_prime_res_obj has not been added since there's a todo to
put a reservation_object into drm_gem_object.

v3: Add todo entry

v2: Drop drm_gem_object_funcs->prime_mmap in favour of
drm_gem_prime_mmap() (Daniel Vetter)

v1:
- drm_gem_object_funcs.map -> .prime_map let it only do PRIME mmap like
  the function it superseeds (Daniel Vetter)
- Flip around the if ladders and make obj->funcs the first choice
  highlighting the fact that this the new default way of doing it
  (Daniel Vetter)

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181110145647.17580-4-noralf@tronnes.org

1 files changed, 6 insertions, 0 deletions

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index abc31956ef15..31ef4adc91c9 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -241,6 +241,12 @@ Most drivers don't need to set drm_driver->gem_prime_import and
 ->gem_prime_export now that drm_gem_prime_import() and drm_gem_prime_export()
 are the default.
 
+struct drm_gem_object_funcs
+---------------------------
+
+GEM objects can now have a function table instead of having the callbacks on the
+DRM driver struct. This is now the preferred way and drivers can be moved over.
+
 Core refactorings
 =================