diff --git a/arch/arm64/boot/dts/renesas/ulcb.dtsi b/arch/arm64/boot/dts/renesas/ulcb.dtsi
index ae36a2e66948..119f2b5024b3 100644
--- a/arch/arm64/boot/dts/renesas/ulcb.dtsi
+++ b/arch/arm64/boot/dts/renesas/ulcb.dtsi
@@ -163,6 +163,8 @@ phy0: ethernet-phy@0 {
 		reg = <0>;
 		interrupts-extended = <&gpio2 11 IRQ_TYPE_LEVEL_LOW>;
 		reset-gpios = <&gpio2 10 GPIO_ACTIVE_LOW>;
+		reset-assert-us = <10000>;
+		reset-deassert-us = <300>;
 	};
 };