diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index a75dbfed016f..25e5f4818e08 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -594,18 +594,6 @@ const struct drm_gem_object_funcs rockchip_gem_object_funcs = {
 	.vm_ops = &drm_gem_dma_vm_ops,
 };
 
-int rockchip_gem_mmap_buf(struct drm_gem_object *obj,
-			  struct vm_area_struct *vma)
-{
-	int ret;
-
-	ret = drm_gem_mmap_obj(obj, obj->size, vma);
-	if (ret)
-		return ret;
-
-	return rockchip_drm_gem_object_mmap(obj, vma);
-}
-
 static struct rockchip_gem_object *
 rockchip_gem_alloc_object(struct drm_device *drm, unsigned int size,
 			  unsigned int flags)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.h b/drivers/gpu/drm/rockchip/rockchip_drm_gem.h
index af588adb31f9..6070544c885d 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.h
@@ -54,9 +54,6 @@ void rockchip_gem_free_object(struct drm_gem_object *obj);
 int rockchip_gem_dumb_create(struct drm_file *file_priv,
 			     struct drm_device *dev,
 			     struct drm_mode_create_dumb *args);
-/* mmap a gem object to userspace. */
-int rockchip_gem_mmap_buf(struct drm_gem_object *obj,
-			  struct vm_area_struct *vma);
 
 /*
  * request gem object creation and buffer allocation as the size