Re: [PATCH v3 1/2] dt-bindings: phy: Add Sophgo CV1800 USB phy

Inochi Amaoto
2024-05-06T12:17:15Z

On Mon, May 06, 2024 at 08:51:59AM GMT, Krzysztof Kozlowski wrote:
> On 05/05/2024 03:52, Inochi Amaoto wrote:
> > The USB phy of Sophgo CV18XX series SoC needs to sense a pin called
> > "VBUS_DET" to get the right operation mode. If this pin is not
> > connected, it only supports setting the mode manually.
> >
> > Add USB phy bindings for Sophgo CV18XX/SG200X series SoC.
>
> ...
>
> > +
> > + clock-names:
> > + items:
> > + - const: phy
> > + - const: app
> > + - const: stb
> > + - const: lpm
> > +
> > + vbus_det-gpios:
>
> No underscores.
>

Thanks.

> > + description: GPIO to the USB OTG VBUS detect pin. This should not be
> > + defined if vbus_det pin and switch pin are connected, which may
> > + break the VBUS detection.
>
> Why is this property of the PHY? VBUS pin goes to the connector, doesn't
> it? It looks like you combined two or three (!!!) bindings into one.
>

Yes, but I am not sure which is the best to write this bindings.
The topology of USB likes this:

controller -- phy -- switch --> (host) port/hub
--> (device) port

The vbus-detect connect to the device port, but it will change the mode for
both phy and switch. And the switch is just a switching circuit.
I am pretty confused on how to split this binding. I think it may like the
following:

phy {
switch {
/* This is the switch in the follows */
connector1 {
/* host port */
};
connector2 {
/* device port*/
/* the vbus pin is here */
};
};
};

Could you share some suggestion on this?

> > + maxItems: 1
> > +
> > + sophgo,switch-gpios:
> > + description: GPIO array for the phy to control connected switch. For
>
> Switch? This is a binding of the phy, not switch...
>

You are right, I think this switch may be more like a pattern device.

> > + host mode, the driver will set these GPIOs to low one by one. For
>
> Yeah, you mention driver which further confirms this is a property for
> driver, not hardware.
>
> Describe your hardware, not driver behavior.

OK, I will remove this.

>
>
> > + device mode, the driver will set these GPIOs to high in reverse
> > + order. For a reference design, see item description.
> > + minItems: 1
> > + items:
> > + - description: USB switch operation mode
> > + - description: USB switch host power control
> > +
> > +required:
> > + - compatible
> > + - "#phy-cells"
> > + - clocks
> > + - clock-names
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + phy@48 {
> > + compatible = "sophgo,cv1800-usb-phy";
> > + reg = <0x48 0x4>;
> > + #phy-cells = <0>;
> > + clocks = <&clk 92>, <&clk 93>,
> > + <&clk 94>, <&clk 95>;
> > + clock-names = "phy", "app", "stb", "lpm";
>
> Make the example complete.
>
>
>
> Best regards,
> Krzysztof