//add the  am57xx-beagle-x15-revc.dts
&mmc3 {
	pinctrl-names = "default", "hs", "sdr12", "sdr25", "sdr50";
	pinctrl-0 = <&mmc3_pins_default>;
	pinctrl-1 = <&mmc3_pins_hs>;
	pinctrl-2 = <&mmc3_pins_sdr12>;
	pinctrl-3 = <&mmc3_pins_sdr25>;
	pinctrl-4 = <&mmc3_pins_sdr50>;
    
	max-frequency = <48000000>;
	vmmc-supply = <&vdd_3v3>;
}; 
*****************************************************************
//add the am57xx-beagle-x15-common.dtsi
&mmc3 {
	status = "okay";

	max-frequency = <48000000>;
	pinctrl-names = "default";
	pinctrl-0 = <&mmc3_pins_ds>;

	bus-width = <4>;
	vmmc-supply = <&vdd_3v3>;
};