[PATCH v2 06/28] drm/bridge: Add drm_private_obj_is_bridge()

[Maxime Ripard <mripard@kernel.org>]

The SRO readout helpers need to distinguish bridge-backed private
objects from other private objects, because bridges require special
readout ordering through the encoder bridge chains.

Add drm_private_obj_is_bridge() which checks whether a private
object's funcs pointer matches the bridge private state funcs.

Signed-off-by: Maxime Ripard <mripard@kernel.org>
---
 drivers/gpu/drm/drm_bridge.c | 15 +++++++++++++++
 include/drm/drm_bridge.h     |  2 ++
 2 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 44d53906e4c5..5b8e171afbe5 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -512,10 +512,25 @@ static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
 	.atomic_create_state = drm_bridge_atomic_create_priv_state,
 	.atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
 	.atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
 };
 
+/**
+ * drm_private_obj_is_bridge - check if a private object backs a bridge
+ * @obj: private object to check
+ *
+ * RETURNS:
+ *
+ * True if @obj is the &drm_private_obj embedded in a &struct drm_bridge,
+ * false otherwise.
+ */
+bool drm_private_obj_is_bridge(struct drm_private_obj *obj)
+{
+	return obj->funcs && obj->funcs == &drm_bridge_priv_state_funcs;
+}
+EXPORT_SYMBOL(drm_private_obj_is_bridge);
+
 static bool drm_bridge_is_atomic(struct drm_bridge *bridge)
 {
 	return bridge->funcs->atomic_reset != NULL;
 }
 
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 84b5517726c1..425f3ca03d95 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1285,10 +1285,12 @@ static inline struct drm_bridge *
 drm_priv_to_bridge(struct drm_private_obj *priv)
 {
 	return container_of(priv, struct drm_bridge, base);
 }
 
+bool drm_private_obj_is_bridge(struct drm_private_obj *obj);
+
 bool drm_bridge_enter(struct drm_bridge *bridge, int *idx);
 void drm_bridge_exit(int idx);
 void drm_bridge_unplug(struct drm_bridge *bridge);
 
 struct drm_bridge *drm_bridge_get(struct drm_bridge *bridge);

-- 
2.53.0