Subject: Re: [PATCH v2 06/10] dt-bindings: phy: mvebu-utmi: add UTMI PHY bindings

From: Miquel Raynal <[email-masked]>
Date: Wed, 16 Jan 2019 14:20:21 +0100

Hi Rob,

Rob Herring <[email-masked]> wrote on Tue, 15 Jan 2019 15:44:29 -0600:

> On Fri, Jan 11, 2019 at 02:31:29PM +0100, Miquel Raynal wrote:
> > Add bindings for Marvell Armada 3700 USB2 UTMI+ PHY.
> > 
> > Signed-off-by: Miquel Raynal <[email-masked]>
> > ---
> >  .../bindings/phy/phy-mvebu-utmi.txt           | 37 +++++++++++++++++++
> >  1 file changed, 37 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/phy/phy-mvebu-utmi.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/phy/phy-mvebu-utmi.txt b/Documentation/devicetree/bindings/phy/phy-mvebu-utmi.txt
> > new file mode 100644
> > index 000000000000..4ade05ce5d51
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/phy/phy-mvebu-utmi.txt
> > @@ -0,0 +1,37 @@
> > +MVEBU A3700 UTMI PHY
> > +--------------------
> > +
> > +USB2 UTMI+ PHY controllers can be found on the following Marvell MVEBU SoCs:
> > +* Armada 3700
> > +
> > +On Armada 3700, there are two USB controllers, one is compatible with the USB2
> > +and USB3 specifications and supports OTG. The other one is USB2 compliant and
> > +only supports host mode. Both of these controllers come with a UTMI PHY.  
> 
> This paragraph says the controllers are different, but are the PHYs 
> different?

Yes they are. I will make it appear clearly in the v3.

> 
> > +
> > +Required Properties:
> > +
> > +- compatible: Should be one of:
> > +	      * "marvell,a3700-utmi-host-phy" for the PHY connected to
> > +	        the USB2 host-only controller.
> > +	      * "marvell,a3700-utmi-otg-phy" for the PHY connected to
> > +	        the USB3 and USB2 OTG capable controller.
> > +- reg: PHY IP register range.
> > +- marvell,usb-misc-reg: handle on the "USB miscellaneous registers" shared
> > +			region covering registers related to both the host
> > +			controller and the PHY.
> > +- #phy-cells: Standard property (Documentation: phy-bindings.txt) Should be 0.
> > +
> > +
> > +Example:
> > +
> > +	usb2_utmi_host_phy: phy@5f000 {
> > +		compatible = "marvell,armada-3700-utmi-host-phy";
> > +		reg = <0x5f000 0x800>;
> > +		marvell,usb-misc-reg = <&usb2_syscon>;
> > +		#phy-cells = <0>;
> > +	};
> > +
> > +	usb2_syscon: system-controller@5f800 {
> > +		compatible = "syscon", "simple-mfd";  
> 
> This is not valid because there's not a specific compatible string and 
> 'simple-mfd' implies there are child nodes.

What do you suggest? Is compatible = "syscon"; enough? This is just an
area with a few registers that do not belong to any specific IP. There
are registers that are related to the control of the USB controller,
and registers that are related to the PHY. It's quite challenging to
find a meaningful specific compatible string. Is it mandatory to add
one? If yes, would "marvell,armada-3700-usb-utmi-{host,otg}-misc" fit?

Thanks,
Miquèl

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