diff --git a/arch/arm/boot/dts/tegra20-colibri-iris.dts b/arch/arm/boot/dts/tegra20-colibri-iris.dts
index 9f0a819c68f2..194f40646a83 100644
--- a/arch/arm/boot/dts/tegra20-colibri-iris.dts
+++ b/arch/arm/boot/dts/tegra20-colibri-iris.dts
@@ -83,6 +83,7 @@ i2c_ddc: i2c@7000c400 {
 		status = "okay";
 	};
 
+	/* EHCI instance 0: USB1_DP/N -> USBC_P/N */
 	usb@c5000000 {
 		status = "okay";
 	};
@@ -92,6 +93,7 @@ usb-phy@c5000000 {
 		vbus-supply = <&reg_usbc_vbus>;
 	};
 
+	/* EHCI instance 2: USB3_DP/N -> USBH_P/N */
 	usb@c5008000 {
 		status = "okay";
 	};
diff --git a/arch/arm/boot/dts/tegra20-colibri.dtsi b/arch/arm/boot/dts/tegra20-colibri.dtsi
index 72dc440ec28a..575e9341a8ef 100644
--- a/arch/arm/boot/dts/tegra20-colibri.dtsi
+++ b/arch/arm/boot/dts/tegra20-colibri.dtsi
@@ -454,6 +454,7 @@ emc-table@333000 {
 		};
 	};
 
+	/* EHCI instance 1: ULPI PHY -> AX88772B (On-module) */
 	usb@c5004000 {
 		status = "okay";
 		nvidia,phy-reset-gpio = <&gpio TEGRA_GPIO(V, 1)