Subject: Re: [net-next RFC PATCH 03/14] dt-bindings: net: document ethernet PHY package nodes

From: Christian Marangi <[email-masked]>
Date: Mon, 20 Nov 2023 17:39:20 +0100

On Mon, Nov 20, 2023 at 10:41:33AM -0700, Rob Herring wrote:
> On Mon, Nov 20, 2023 at 02:50:30PM +0100, Christian Marangi wrote:
> > Document ethernet PHY package nodes used to describe PHY shipped in
> > bundle of 4-5 PHY. These particular PHY require specific PHY in the
> > package for global onfiguration of the PHY package.
> > 
> > Example are PHY package that have some regs only in one PHY of the
> > package and will affect every other PHY in the package, for example
> > related to PHY interface mode calibration or global PHY mode selection.
> > 
> > The PHY package node should use the global-phys property and the
> > global-phy-names to define PHY in the package required by the PHY driver
> > for global configuration.
> > 
> > It's also possible to specify the property phy-mode to specify that the
> > PHY package sets a global PHY interface mode and every PHY of the
> > package requires to have the same PHY interface mode.
> > 
> > Signed-off-by: Christian Marangi <[email-masked]>
> > ---
> >  .../bindings/net/ethernet-phy-package.yaml    | 86 +++++++++++++++++++
> >  1 file changed, 86 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/net/ethernet-phy-package.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/net/ethernet-phy-package.yaml b/Documentation/devicetree/bindings/net/ethernet-phy-package.yaml
> > new file mode 100644
> > index 000000000000..2aa109e155d9
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/net/ethernet-phy-package.yaml
> > @@ -0,0 +1,86 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/net/ethernet-phy-package.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Ethernet PHY Package Common Properties
> > +
> > +maintainers:
> > +  - Christian Marangi <[email-masked]
> 
> Missing a '>'
> 
> > +
> > +properties:
> > +  $nodename:
> > +    pattern: "^ethernet-phy-package(-[0-9]+)?$"
> > +
> > +  compatible:
> > +    const: ethernet-phy-package
> > +
> > +  '#address-cells':
> > +    description: number of address cells for the MDIO bus
> > +    const: 1
> > +
> > +  '#size-cells':
> > +    description: number of size cells on the MDIO bus
> > +    const: 0
> > +
> > +  global-phys:
> > +    $ref: /schemas/types.yaml#/definitions/phandle-array
> > +    minItems: 1
> > +    maxItems: 31
> > +    description:
> > +      List of phandle to the PHY in the package required and
> > +      used to configure the PHY package.
> > +
> > +  global-phy-names:
> > +    $ref: /schemas/types.yaml#/definitions/string-array
> > +    minItems: 1
> > +    maxItems: 31
> > +    description:
> > +      List of names of the PHY defined in global-phys.
> > +
> > +  phy-connection-type:
> > +    $ref: /schemas/net/ethernet-phy-mode-types.yaml#definitions/phy-connection-type
> > +    description:
> > +      Specifies global interface type for the PHY package.
> > +
> > +  phy-mode:
> > +    $ref: "#/properties/phy-connection-type"
> > +
> > +patternProperties:
> > +  ^ethernet-phy(@[a-f0-9]+)?$:
> > +    $ref: /schemas/net/ethernet-phy.yaml#
> > +
> > +required:
> > +  - compatible
> > +
> > +dependencies:
> > +  global-phy-names: [global-phys]
> > +
> > +unevaluatedProperties: false
> > +
> > +examples:
> > +  - |
> > +    ethernet {
> 
> You mean 'mdio' here, right?
> 
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        ethernet-phy-package {
> 
> This doesn't work. Child nodes of MDIO bus must be an MDIO device with 
> an address. What you need is a node with all the addresses of the 
> device:
> 
> mdio {
>   ...
> 
>   ethernet-phy@1 {
>     compatible = "vendor,specifc-compatible-for-device";
>     reg = <1>, <4>;
>     ...
>   };
> };
> 
> There's also some MDIO devices which define a secondary address as a 
> child device. Maybe those are similar to your situation. I don't recall 
> which ones offhand.
>

Ehh this is not really a situation. We really need a way to describe PHY
package. (In the sense of device that expose multiple PHY package, as
they can be treated as single one but they are actually in bulk of 2-4-5
PHY)

qca807x is one example, quickinc is trying to push another PHY with just
a similar implementation and Maxime Chevallier just pointed out that Marvell
Alaska 88e1543 PHY also have this kind of configuration.

I feel defining PHY in subnode is a MUST and using ethernet-phy might be
confusing to describe PHY package (so I think a brand new node name
might be a better solution)

About the reg, I wonder if it would like it more if the PHY package node
would include the reg as the first address of the package and the reg
property as a list of all the reg the PHY package use.

Something like this?

        ethernet-phy-package@1 {
            compatible = "ethernet-phy-package";
            #address-cells = <1>;
            #size-cells = <0>;
            reg = <1>, <2>, <3>, <4>;

            global-phys = <&phy4>;
            global-phy-names = "base";

            ethernet-phy@1 {
              compatible = "ethernet-phy-ieee802.3-c22";
              reg = <1>;
            };

            phy4: ethernet-phy@4 {
              compatible = "ethernet-phy-ieee802.3-c22";
              reg = <4>;
            };
        };

Thanks a lot for the review and I hope we can find a good and correct
way to model this. Just hope we don't have to add all kind of proprerty
to describe the idea of PHY package. (I think the current example makes
it very clear that the PHY under the node are all part of a single piece
on the device)

> > +            compatible = "ethernet-phy-package";
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +
> > +            global-phys = <&phy4>;
> > +            global-phy-names = "base";
> > +
> > +            ethernet-phy@1 {
> > +              compatible = "ethernet-phy-ieee802.3-c22";
> > +              reg = <1>;
> > +            };
> > +
> > +            phy4: ethernet-phy@4 {
> > +              compatible = "ethernet-phy-ieee802.3-c22";
> > +              reg = <4>;
> > +            };
> > +        };
> > +    };
> > -- 
> > 2.40.1
> > 

-- 
	Ansuel