diff --git a/arch/arm64/boot/dts/renesas/ulcb.dtsi b/arch/arm64/boot/dts/renesas/ulcb.dtsi
index 3e7a6b94e9f8..6f814845f8b6 100644
--- a/arch/arm64/boot/dts/renesas/ulcb.dtsi
+++ b/arch/arm64/boot/dts/renesas/ulcb.dtsi
@@ -146,6 +146,7 @@
 	pinctrl-0 = <&avb_pins>;
 	pinctrl-names = "default";
 	phy-handle = <&phy0>;
+	phy-mode = "rgmii-txid";
 	status = "okay";
 
 	phy0: ethernet-phy@0 {