diff --git a/Documentation/devicetree/bindings/net/rockchip-dwmac.txt b/Documentation/devicetree/bindings/net/rockchip-dwmac.txt
index 2362dcd5afc9d39782cb4d4bc51c77997a2a7f35..21fd199e89b5c34ed9d4f7a361b86d5c155fb34b 100644
--- a/Documentation/devicetree/bindings/net/rockchip-dwmac.txt
+++ b/Documentation/devicetree/bindings/net/rockchip-dwmac.txt
@@ -33,6 +33,7 @@ Required properties:
 Optional properties:
  - tx_delay: Delay value for TXD timing. Range value is 0~0x7F, 0x30 as default.
  - rx_delay: Delay value for RXD timing. Range value is 0~0x7F, 0x10 as default.
+ - phy-supply: phandle to a regulator if the PHY needs one
 
 Example: