Hi Rob, Sorry for the delayed response. I had a vacation in last week. > From: Rob Herring, Sent: Saturday, April 28, 2018 5:06 AM > > On Thu, Apr 26, 2018 at 08:26:41PM +0900, Yoshihiro Shimoda wrote: > > This patch adds a new documentation for Renesas R-Car USB 3.0 role > > switch that can change the USB 3.0 role to either host or peripheral > > by a hardware register that is included in USB3.0 peripheral module. > > > > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> > > --- > > .../bindings/usb/renesas,rcar-usb3-role-sw.txt | 47 ++++++++++++++++++++++ > > 1 file changed, 47 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/usb/renesas,rcar-usb3-role-sw.txt > > > > diff --git a/Documentation/devicetree/bindings/usb/renesas,rcar-usb3-role-sw.txt > b/Documentation/devicetree/bindings/usb/renesas,rcar-usb3-role-sw.txt > > new file mode 100644 > > index 0000000..e074c03 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/usb/renesas,rcar-usb3-role-sw.txt > > @@ -0,0 +1,47 @@ > > +Renesas Electronics R-Car USB 3.0 role switch > > + > > +A renesas_usb3's node can contain this node. > > + > > +Required properties: > > + - compatible: Must contain "renesas,rcar-usb3-role-switch". > > + > > +Required nodes: > > + - The connection to a usb3.0 host node needs by using OF graph bindings. > > + - port@0 = USB 3.0 host port > > + - port@1 = USB 3.0 peripheral port > > + > > +Example of R-Car H3 ES2.0: > > + usb3_peri0: usb@ee020000 { > > + compatible = "renesas,r8a7795-usb3-peri", > > + "renesas,rcar-gen3-usb3-peri"; > > + reg = <0 0xee020000 0 0x400>; > > + interrupts = <GIC_SPI 104 IRQ_TYPE_LEVEL_HIGH>; > > + clocks = <&cpg CPG_MOD 328>; > > + power-domains = <&sysc R8A7795_PD_ALWAYS_ON>; > > + resets = <&cpg 328>; > > + > > + usb3-role-sw { > > + compatible = "renesas,rcar-usb3-role-switch"; > > You don't define any h/w resources. How is this device accessed? This device accesses one of registers in the usb3_peri0. In the detail, the usb3-role-sw uses 0xee020218 (32-bit register) only. (Unfortunately, the hardware design is not good...) In this case, should I describe the following in the usb3-role-sw node? reg = <0 0xee020218 0 4>; Or, shouldn't I add the usb3-role-sw node and a driver for usb3_peri0 should take care for it? Best regards, Yoshihiro Shimoda