drm/atomic: track bitmask of planes attached to crtc

Chasing plane->state->crtc of planes that are *not* part of the same
atomic update is racy, making it incredibly awkward (or impossible) to
do something simple like iterate over all planes and figure out which
ones are attached to a crtc.

Solve this by adding a bitmask of currently attached planes in the
crtc-state.

Note that the transitional helpers do not maintain the plane_mask.  But
they only support the legacy ioctls, which have sufficient brute-force
locking around plane updates that they can continue to loop over all
planes to see what is attached to a crtc the old way.

Signed-off-by: Rob Clark <robdclark@gmail.com>
[danvet:
- Drop comments about locking in set_crtc_for_plane since they're a
  bit misleading - we already should hold lock for the current crtc.
- Also WARN_ON if get_state on the old crtc fails since that should
  have been done already.
- Squash in fixup to check get_plane_state return value, reported by
  Dan Carpenter and acked by Rob Clark.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index e224ccfa11ca..ad2229574dd9 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -46,8 +46,8 @@ drm_atomic_get_connector_state(struct drm_atomic_state *state,
 			       struct drm_connector *connector);
 
 int __must_check
-drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
-			      struct drm_crtc *crtc);
+drm_atomic_set_crtc_for_plane(struct drm_atomic_state *state,
+			      struct drm_plane *plane, struct drm_crtc *crtc);
 void drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
 				 struct drm_framebuffer *fb);
 int __must_check