diff --git a/arch/arm/boot/dts/rk3066a.dtsi b/arch/arm/boot/dts/rk3066a.dtsi
index f3a51099f5e03ead4d938047acdf3305b1ab1c5a..fc8dcc72b16f78070cc83f1e2426b84d76d68024 100644
--- a/arch/arm/boot/dts/rk3066a.dtsi
+++ b/arch/arm/boot/dts/rk3066a.dtsi
@@ -636,6 +636,8 @@
 };
 
 &mmc0 {
+	clock-frequency = <50000000>;
+	max-frequency = <50000000>;
 	pinctrl-names = "default";
 	pinctrl-0 = <&sd0_clk &sd0_cmd &sd0_cd &sd0_bus4>;
 };