diff --git a/Documentation/devicetree/bindings/sound/renesas,rsnd.txt b/Documentation/devicetree/bindings/sound/renesas,rsnd.txt
index c57cbd65736cfaf4bd67c0801fcd86dca19ef106..bbcb3272977d4d559fe5a6519f399de045e6a71f 100644
--- a/Documentation/devicetree/bindings/sound/renesas,rsnd.txt
+++ b/Documentation/devicetree/bindings/sound/renesas,rsnd.txt
@@ -34,6 +34,8 @@ Required properties:
 				  see below for detail.
 - #sound-dai-cells		: it must be 0 if your system is using single DAI
 				  it must be 1 if your system is using multi  DAI
+
+Optional properties:
 - #clock-cells			: it must be 0 if your system has audio_clkout
 				  it must be 1 if your system has audio_clkout0/1/2/3
 - clock-frequency		: for all audio_clkout0/1/2/3