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diff --git a/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt b/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
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+Rockchip EMMC PHY
+-----------------------
+
+Required properties:
+ - compatible: rockchip,rk3399-emmc-phy
+ - #phy-cells: must be 0
+ - reg: PHY register address offset and length in "general
+   register files"
+
+Optional properties:
+ - clock-names: Should contain "emmcclk".  Although this is listed as optional
+		(because most boards can get basic functionality without having
+		access to it), it is strongly suggested.
+		See ../clock/clock-bindings.txt for details.
+ - clocks: Should have a phandle to the card clock exported by the SDHCI driver.
+ - drive-impedance-ohm: Specifies the drive impedance in Ohm.
+                        Possible values are 33, 40, 50, 66 and 100.
+                        If not set, the default value of 50 will be applied.
+ - rockchip,enable-strobe-pulldown: Enable internal pull-down for the strobe
+                                    line.  If not set, pull-down is not used.
+ - rockchip,output-tapdelay-select: Specifies the phyctrl_otapdlysec register.
+                                    If not set, the register defaults to 0x4.
+                                    Maximum value 0xf.
+
+Example:
+
+
+grf: syscon@ff770000 {
+	compatible = "rockchip,rk3399-grf", "syscon", "simple-mfd";
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+...
+
+	emmcphy: phy@f780 {
+		compatible = "rockchip,rk3399-emmc-phy";
+		reg = <0xf780 0x20>;
+		clocks = <&sdhci>;
+		clock-names = "emmcclk";
+		drive-impedance-ohm = <50>;
+		#phy-cells = <0>;
+	};
+};