RE: [PATCH/RFC v2 1/6] dt-bindings: usb: add Renesas R-Car USB 3.0 role switch

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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

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