return ret;
 }
 
-static int sti_atomic_check(struct drm_device *dev,
-                           struct drm_atomic_state *state)
-{
-       int ret;
-
-       ret = drm_atomic_helper_check_modeset(dev, state);
-       if (ret)
-               return ret;
-
-       ret = drm_atomic_normalize_zpos(dev, state);
-       if (ret)
-               return ret;
-
-       ret = drm_atomic_helper_check_planes(dev, state);
-       if (ret)
-               return ret;
-
-       return ret;
-}
-
 static const struct drm_mode_config_funcs sti_mode_config_funcs = {
        .fb_create = drm_gem_fb_create,
        .output_poll_changed = drm_fb_helper_output_poll_changed,
-       .atomic_check = sti_atomic_check,
+       .atomic_check = drm_atomic_helper_check,
        .atomic_commit = drm_atomic_helper_commit,
 };
 
        dev->mode_config.max_height = STI_MAX_FB_HEIGHT;
 
        dev->mode_config.funcs = &sti_mode_config_funcs;
+
+       dev->mode_config.normalize_zpos = true;
 }
 
 DEFINE_DRM_GEM_CMA_FOPS(sti_driver_fops);