Re: [linux-sunxi] Re: [PATCH v4 07/10] dt-bindings: phy: add binding for Allwinner USB3 PHY

From: Icenowy Zheng <icenowy@aosc.io>
To: robh@kernel.org, Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	linux-sunxi <linux-sunxi@googlegroups.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Chen-Yu Tsai <wens@csie.org>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [linux-sunxi] Re: [PATCH v4 07/10] dt-bindings: phy: add binding for Allwinner USB3 PHY
Date: Fri, 19 Oct 2018 13:54:10 +0800	[thread overview]
Message-ID: <6A511BD2-AF0F-40E5-B1B4-F37BC8D7263E@aosc.io> (raw)
In-Reply-To: <CAL_JsqL=YY2K0KPK-fN1O-a3R4o5GwYUZr9wyA2DOaXc29Hh3g@mail.gmail.com>

于 2018年10月18日 GMT+08:00 下午9:58:25, Rob Herring <robh@kernel.org> 写到:
>On Sat, Oct 13, 2018 at 9:42 PM Icenowy Zheng <icenowy@aosc.io> wrote:
>>
>> 在 2018-10-05五的 15:58 -0500，Rob Herring写道：
>> > On Thu, Oct 04, 2018 at 08:28:52PM +0800, Icenowy Zheng wrote:
>> > > The new Allwinner H6 SoC contains a USB3 PHY that is wired to the
>> > > external USB3 pins of the SoC.
>> > >
>> > > Add a device tree binding for the PHY.
>> > >
>> > > Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
>> > > Reviewed-by: Chen-Yu Tsai <wens@csie.org>
>> > > ---
>> > > Changes in v4:
>> > > - Changed Vbus regulator property to vbus-supply.
>> > >
>> > > Changes in v3:
>> > > - Added Chen-Yu's Review tag.
>> > >
>> > > No changes in v2, v1.
>> > >
>> > >  .../bindings/phy/sun50i-usb3-phy.txt          | 23
>> > > +++++++++++++++++++
>> > >  1 file changed, 23 insertions(+)
>> > >  create mode 100644 Documentation/devicetree/bindings/phy/sun50i-
>> > > usb3-phy.txt
>> > >
>> > > diff --git a/Documentation/devicetree/bindings/phy/sun50i-usb3-
>> > > phy.txt
>b/Documentation/devicetree/bindings/phy/sun50i-usb3-phy.txt
>> > > new file mode 100644
>> > > index 000000000000..9f49c6b8c7e7
>> > > --- /dev/null
>> > > +++ b/Documentation/devicetree/bindings/phy/sun50i-usb3-phy.txt
>> > > @@ -0,0 +1,23 @@
>> > > +Allwinner sun50i USB3 PHY
>> > > +-----------------------
>> > > +
>> > > +Required properties:
>> > > +- compatible : should be one of
>> > > +  * allwinner,sun60i-h6-usb3-phy
>> > > +- reg : a list of offset + length pairs
>> > > +- #phy-cells : from the generic phy bindings, must be 0
>> > > +- clocks : phandle + clock specifier for the phy clock
>> > > +- resets : phandle + reset specifier for the phy reset
>> > > +
>> > > +Optional Properties:
>> > > +- vbus-supply : a phandle to a regulator that provides power to
>> > > VBUS.
>> >
>> > This belongs in a connector node as it is part of the connector
>> > unless
>> > the phy physically needs Vbus for power.
>> >
>> > But others have done this, so all the phys can just be wrong...
>>
>> How should we reference the connector?
>>
>> Via OF graph or simply a property in PHY node?
>
>The connector is either a child of the controller or an OF graph from
>the controller to the connector. The phy driver needs the controller
>node and then it can walk the tree or graph to get the connector node.

Why is it a child of the controller?

I think on hardware the connector is connected to the PHY via USB, and PHY is
connected to the controller via ULPI/UTMI and PIPE, so the connector node
should link to PHY in some way, not to controller.

For Allwinner USB3 PHY I prefer to use child node now, as it's a simple
single-port PHY, and there seems to be no reserved space for multi-port.

>
>Rob