}
 }
 
-static void
-set_routing_links(struct drm_device *dev, struct drm_atomic_state *old_state)
+/**
+ * drm_atomic_helper_update_legacy_modeset_state - update legacy modeset state
+ * @dev: DRM device
+ * @old_state: atomic state object with old state structures
+ *
+ * This function updates all the various legacy modeset state pointers in
+ * connectors, encoders and crtcs. It also updates the timestamping constants
+ * used for precise vblank timestamps by calling
+ * drm_calc_timestamping_constants().
+ *
+ * Drivers can use this for building their own atomic commit if they don't have
+ * a pure helper-based modeset implementation.
+ */
+void
+drm_atomic_helper_update_legacy_modeset_state(struct drm_device *dev,
+                                             struct drm_atomic_state *old_state)
 {
        struct drm_connector *connector;
        struct drm_connector_state *old_conn_state;
                                                        &crtc->state->adjusted_mode);
        }
 }
+EXPORT_SYMBOL(drm_atomic_helper_update_legacy_modeset_state);
 
 static void
 crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *old_state)
                                               struct drm_atomic_state *old_state)
 {
        disable_outputs(dev, old_state);
-       set_routing_links(dev, old_state);
+
+       drm_atomic_helper_update_legacy_modeset_state(dev, old_state);
+
        crtc_set_mode(dev, old_state);
 }
 EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_disables);
 
 void drm_atomic_helper_wait_for_vblanks(struct drm_device *dev,
                                        struct drm_atomic_state *old_state);
 
+void
+drm_atomic_helper_update_legacy_modeset_state(struct drm_device *dev,
+                                             struct drm_atomic_state *old_state);
+
 void drm_atomic_helper_commit_modeset_disables(struct drm_device *dev,
                                               struct drm_atomic_state *state);
 void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,