drm: Add drm_atomic_get_old/new_private_obj_state

This pair of functions return the old/new private object state for the
given private_obj, or NULL if the private_obj is not part of the global
atomic state.
Reviewed-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
Signed-off-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

drivers/gpu/drm/drm_atomic.c

@@ -797,6 +797,50 @@ drm_atomic_get_private_obj_state(struct drm_atomic_state *state,
 }
 EXPORT_SYMBOL(drm_atomic_get_private_obj_state);
 
+/**
+ * drm_atomic_get_old_private_obj_state
+ * @state: global atomic state object
+ * @obj: private_obj to grab
+ *
+ * This function returns the old private object state for the given private_obj,
+ * or NULL if the private_obj is not part of the global atomic state.
+ */
+struct drm_private_state *
+drm_atomic_get_old_private_obj_state(struct drm_atomic_state *state,
+				     struct drm_private_obj *obj)
+{
+	int i;
+
+	for (i = 0; i < state->num_private_objs; i++)
+		if (obj == state->private_objs[i].ptr)
+			return state->private_objs[i].old_state;
+
+	return NULL;
+}
+EXPORT_SYMBOL(drm_atomic_get_old_private_obj_state);
+
+/**
+ * drm_atomic_get_new_private_obj_state
+ * @state: global atomic state object
+ * @obj: private_obj to grab
+ *
+ * This function returns the new private object state for the given private_obj,
+ * or NULL if the private_obj is not part of the global atomic state.
+ */
+struct drm_private_state *
+drm_atomic_get_new_private_obj_state(struct drm_atomic_state *state,
+				     struct drm_private_obj *obj)
+{
+	int i;
+
+	for (i = 0; i < state->num_private_objs; i++)
+		if (obj == state->private_objs[i].ptr)
+			return state->private_objs[i].new_state;
+
+	return NULL;
+}
+EXPORT_SYMBOL(drm_atomic_get_new_private_obj_state);
+
 /**
  * drm_atomic_get_connector_state - get connector state
  * @state: global atomic state object
@@ -1236,4 +1280,3 @@ int drm_atomic_debugfs_init(struct drm_minor *minor)
 			minor->debugfs_root, minor);
 }
 #endif
-

include/drm/drm_atomic.h

@@ -452,6 +452,12 @@ void drm_atomic_private_obj_fini(struct drm_private_obj *obj);
 struct drm_private_state * __must_check
 drm_atomic_get_private_obj_state(struct drm_atomic_state *state,
 				 struct drm_private_obj *obj);
+struct drm_private_state *
+drm_atomic_get_old_private_obj_state(struct drm_atomic_state *state,
+				     struct drm_private_obj *obj);
+struct drm_private_state *
+drm_atomic_get_new_private_obj_state(struct drm_atomic_state *state,
+				     struct drm_private_obj *obj);
 
 /**
  * drm_atomic_get_existing_crtc_state - get crtc state, if it exists