return state->fb && state->crtc;
 }
 
-struct drm_plane_state *vc4_plane_duplicate_state(struct drm_plane *plane)
+static struct drm_plane_state *vc4_plane_duplicate_state(struct drm_plane *plane)
 {
        struct vc4_plane_state *vc4_state;
 
        return &vc4_state->base;
 }
 
-void vc4_plane_destroy_state(struct drm_plane *plane,
-                            struct drm_plane_state *state)
+static void vc4_plane_destroy_state(struct drm_plane *plane,
+                                   struct drm_plane_state *state)
 {
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
 
 }
 
 /* Called during init to allocate the plane's atomic state. */
-void vc4_plane_reset(struct drm_plane *plane)
+static void vc4_plane_reset(struct drm_plane *plane)
 {
        struct vc4_plane_state *vc4_state;