diff --git a/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml b/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml
index f80fcbc3128b..5b046932fbc3 100644
--- a/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml
+++ b/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml
@@ -64,6 +64,7 @@ properties:
 
   samsung,mode:
     $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [0, 1, 2, 3]
     description:
       Selects USI function (which serial protocol to use). Refer to
       <include/dt-bindings/soc/samsung,exynos-usi.h> for valid USI mode values.