diff --git a/Documentation/devicetree/bindings/tty/serial/of-serial.txt b/Documentation/devicetree/bindings/tty/serial/of-serial.txt
index ba385f2e0ddc5777daf3f7e9d667e6727ec4c26d..1e1145ca4f3c2cb192f7e4bf5ce95f6c73ba0801 100644
--- a/Documentation/devicetree/bindings/tty/serial/of-serial.txt
+++ b/Documentation/devicetree/bindings/tty/serial/of-serial.txt
@@ -14,7 +14,10 @@ Required properties:
 	- "serial" if the port type is unknown.
 - reg : offset and length of the register set for the device.
 - interrupts : should contain uart interrupt.
-- clock-frequency : the input clock frequency for the UART.
+- clock-frequency : the input clock frequency for the UART
+	 or
+  clocks phandle to refer to the clk used as per Documentation/devicetree
+  /bindings/clock/clock-bindings.txt
 
 Optional properties:
 - current-speed : the current active speed of the UART.