linux-kernel - Re: [PATCH net-next v1 1/7] dt-bindings: net: pse-dt: add bindings for generic PSE controller

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Message-ID: <20220823162257.GO10138@pengutronix.de>
Date:   Tue, 23 Aug 2022 18:22:57 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Rob Herring <robh@...nel.org>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Jonathan Corbet <corbet@....net>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
        David Jander <david@...tonic.nl>
Subject: Re: [PATCH net-next v1 1/7] dt-bindings: net: pse-dt: add bindings
 for generic PSE controller

On Mon, Aug 22, 2022 at 01:41:12PM -0500, Rob Herring wrote:
> On Fri, Aug 19, 2022 at 02:01:03PM +0200, Oleksij Rempel wrote:
> > Add binding for generic Ethernet PSE controller.
> > 
> > Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> > ---
> >  .../bindings/net/pse-pd/generic-pse.yaml      | 40 +++++++++++++++++++
> >  1 file changed, 40 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/net/pse-pd/generic-pse.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/net/pse-pd/generic-pse.yaml b/Documentation/devicetree/bindings/net/pse-pd/generic-pse.yaml
> > new file mode 100644
> > index 0000000000000..64f91efa79a56
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/net/pse-pd/generic-pse.yaml
> > @@ -0,0 +1,40 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/net/pse-pd/generic-pse.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Generic Power Sourcing Equipment
> > +
> > +maintainers:
> > +  - Oleksij Rempel <o.rempel@...gutronix.de>
> > +
> > +description: |
> > +  Generic PSE controller. The device must be referenced by the PHY node
> > +  to control power injection to the Ethernet cable.
> 
> Isn't this separate from the PHY other than you need to associate 
> supplies with ethernet ports?
> 
> Is there a controller here? Or it is just a regulator consumer 
> associated with an ethernet port?

Current version has only regulator. It will be extended with IEEE 802.3
specific power source classification information, wich will be overkill for the
regulator framework. I can add it to the v2 version.

> > +properties:
> > +  compatible:
> > +    const: ieee802.3-podl-pse-generic
> 
> Is this for 802.3bu only (which is where PoDL comes from) or all the 
> flavors? If all, do they need to be distinguished?

yes. ieee802.3 defines type and class with different enumeration and
meanings for PSE and PoDL PSE. 

So far we have two different modes:
 - 802.3bu (PoDL PSE). Has own types and classes
 - 802.3af  is extended by 802.3at, and the extended by 802.3bt
   all of them are named as PSE and has own types and classes as well.

I worry more about the fact is some one will implement HW supporting both
modes. IMO, it is possible to take usual ethernet PHY, configure to
10Bit half-duplex and run over single pair. In this case it is possible
to use only PoDL PSE mode.

In this case I need single generic compatible but different properties
to describe supported PSE and PoDL PSE modes.

> 'generic' is redundant.

ok

> > +
> > +  '#pse-cells':
> 
> What's this for? You don't have a consumer.

the consumer is PHY.

> > +    const: 0
> > +
> > +  ieee802.3-podl-pse-supply:
> 
> Seems a bit long

ok. Reduce it to pse-supply ?

> > +    description: |
> 
> Don't need '|' if no formatting to maintain.

ok

> > +      Power supply for the PSE controller
> > +
> > +additionalProperties: false
> > +
> > +required:
> > +  - compatible
> > +  - '#pse-cells'
> > +  - ieee802.3-podl-pse-supply
> > +
> > +examples:
> > +  - |
> > +    ethernet-pse-1 {
> > +      compatible = "ieee802.3-podl-pse-generic";
> > +      ieee802.3-podl-pse-supply = <&reg_t1l1>;
> > +      #pse-cells = <0>;
> > +    };
> > -- 
> > 2.30.2
> > 
> > 
> 

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