diff --git a/Documentation/devicetree/bindings/input/touchscreen/cypress,tt21000.yaml b/Documentation/devicetree/bindings/input/touchscreen/cypress,tt21000.yaml
index 4080422a9eb5..037e5d3c447f 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/cypress,tt21000.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/cypress,tt21000.yaml
@@ -34,6 +34,9 @@ properties:
   vdd-supply:
     description: Regulator for voltage.
 
+  vddio-supply:
+    description: Optional Regulator for I/O voltage.
+
   reset-gpios:
     maxItems: 1