diff --git a/arch/arm/boot/dts/r8a7790-lager.dts b/arch/arm/boot/dts/r8a7790-lager.dts
index 636d53bb87a2..2bc20e44fff9 100644
--- a/arch/arm/boot/dts/r8a7790-lager.dts
+++ b/arch/arm/boot/dts/r8a7790-lager.dts
@@ -579,6 +579,7 @@
 	pinctrl-0 = <&sound_pins &sound_clk_pins>;
 	pinctrl-names = "default";
 
+	/* Single DAI */
 	#sound-dai-cells = <0>;
 
 	status = "okay";
diff --git a/arch/arm/boot/dts/r8a7790.dtsi b/arch/arm/boot/dts/r8a7790.dtsi
index 7cef4d9f0377..1543fa5f21d5 100644
--- a/arch/arm/boot/dts/r8a7790.dtsi
+++ b/arch/arm/boot/dts/r8a7790.dtsi
@@ -1397,7 +1397,12 @@
 	};
 
 	rcar_sound: rcar_sound@ec500000 {
-		#sound-dai-cells = <1>;
+		/*
+		 * #sound-dai-cells is required
+		 *
+		 * Single DAI : #sound-dai-cells = <0>;         <&rcar_sound>;
+		 * Multi  DAI : #sound-dai-cells = <1>;         <&rcar_sound N>;
+		 */
 		compatible =  "renesas,rcar_sound-r8a7790", "renesas,rcar_sound-gen2";
 		reg =	<0 0xec500000 0 0x1000>, /* SCU */
 			<0 0xec5a0000 0 0x100>,  /* ADG */