if (WARN_ON(IS_ERR(crtc_state)))
                        return PTR_ERR(crtc_state);
 
-               crtc_state->plane_mask &= ~(1 << drm_plane_index(plane));
+               crtc_state->plane_mask &= ~drm_plane_mask(plane);
        }
 
        plane_state->crtc = crtc;
                                                       crtc);
                if (IS_ERR(crtc_state))
                        return PTR_ERR(crtc_state);
-               crtc_state->plane_mask |= (1 << drm_plane_index(plane));
+               crtc_state->plane_mask |= drm_plane_mask(plane);
        }
 
        if (crtc)
 
                                     struct drm_crtc_state *state)
 {
        bool has_primary = state->plane_mask &
-                          BIT(drm_plane_index(crtc->primary));
+                          drm_plane_mask(crtc->primary);
 
        /* We always want to have an active plane with an active CRTC */
        if (has_primary != state->enable)
 
  * Given a registered plane, return the index of that plane within a DRM
  * device's list of planes.
  */
-static inline unsigned int drm_plane_index(struct drm_plane *plane)
+static inline unsigned int drm_plane_index(const struct drm_plane *plane)
 {
        return plane->index;
 }
+
+/**
+ * drm_plane_mask - find the mask of a registered plane
+ * @plane: plane to find mask for
+ */
+static inline u32 drm_plane_mask(const struct drm_plane *plane)
+{
+       return 1 << drm_plane_index(plane);
+}
+
 struct drm_plane * drm_plane_from_index(struct drm_device *dev, int idx);
 void drm_plane_force_disable(struct drm_plane *plane);
 
  */
 #define drm_for_each_plane_mask(plane, dev, plane_mask) \
        list_for_each_entry((plane), &(dev)->mode_config.plane_list, head) \
-               for_each_if ((plane_mask) & (1 << drm_plane_index(plane)))
+               for_each_if ((plane_mask) & drm_plane_mask(plane))
 
 /**
  * drm_for_each_legacy_plane - iterate over all planes for legacy userspace