drm/atomic: add drm_atomic_set_fence_for_plane()

This new function should be used by drivers when setting a implicit
fence for the plane. It abstracts the fact that the user might have
chosen explicit fencing instead.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1478513013-3221-1-git-send-email-gustavo@padovan.org
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index fc8af53..2d1e9c9 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -345,6 +345,8 @@ drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
 			      struct drm_crtc *crtc);
 void drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
 				 struct drm_framebuffer *fb);
+void drm_atomic_set_fence_for_plane(struct drm_plane_state *plane_state,
+				    struct dma_fence *fence);
 int __must_check
 drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
 				  struct drm_crtc *crtc);