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 <[e-mail]>
Signed-off-by: James Qian Wang (Arm Technology China) <[e-mail]>
Signed-off-by: Liviu Dudau <[e-mail]>

drivers/gpu/drm/drm_atomic.c

···
 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
  * @connector: connector to get state object for
···
 			minor->debugfs_root, minor);
 }
 #endif
-

include/drm/drm_atomic.h

···
 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