diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index 74c8972f9dc3..71c428e2d8f2 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -866,32 +866,6 @@ void rockchip_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
 	/* Nothing to do if allocated by DMA mapping API. */
 }
 
-static int rockchip_gem_dumb_map_offset(struct drm_file *file_priv,
-					struct drm_device *dev, uint32_t handle,
-					uint64_t *offset)
-{
-	struct drm_gem_object *obj;
-	int ret;
-
-	obj = drm_gem_object_lookup(file_priv, handle);
-	if (!obj) {
-		DRM_ERROR("failed to lookup gem object.\n");
-		return -EINVAL;
-	}
-
-	ret = drm_gem_create_mmap_offset(obj);
-	if (ret)
-		goto out;
-
-	*offset = drm_vma_node_offset_addr(&obj->vma_node);
-	DRM_DEBUG_KMS("offset = 0x%llx\n", *offset);
-
-out:
-	drm_gem_object_put_locked(obj);
-
-	return 0;
-}
-
 int rockchip_gem_create_ioctl(struct drm_device *dev, void *data,
 			      struct drm_file *file_priv)
 {
@@ -908,8 +882,8 @@ int rockchip_gem_map_offset_ioctl(struct drm_device *drm, void *data,
 {
 	struct drm_rockchip_gem_map_off *args = data;
 
-	return rockchip_gem_dumb_map_offset(file_priv, drm, args->handle,
-					    &args->offset);
+	return drm_gem_dumb_map_offset(file_priv, drm, args->handle,
+				       &args->offset);
 }
 
 int rockchip_gem_get_phys_ioctl(struct drm_device *dev, void *data,