netdev - Re: [PATCH v1 1/1] dt-bindings: net: dsa: Add DSA yaml binding

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Message-ID: <8c105489-42c5-b4ba-73b6-c3a858f646a6@gmail.com>
Date:   Fri, 10 Jul 2020 10:20:51 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Rob Herring <robh@...nel.org>, Kurt Kanzenbach <kurt@...utronix.de>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v1 1/1] dt-bindings: net: dsa: Add DSA yaml binding



On 7/10/2020 9:45 AM, Rob Herring wrote:
> On Fri, Jul 10, 2020 at 11:06:18AM +0200, Kurt Kanzenbach wrote:
>> For future DSA drivers it makes sense to add a generic DSA yaml binding which
>> can be used then. This was created using the properties from dsa.txt. It
>> includes the ports and the dsa,member property.
>>
>> Suggested-by: Florian Fainelli <f.fainelli@...il.com>
>> Signed-off-by: Kurt Kanzenbach <kurt@...utronix.de>
>> ---
>>  .../devicetree/bindings/net/dsa/dsa.yaml      | 80 +++++++++++++++++++
>>  1 file changed, 80 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/net/dsa/dsa.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/net/dsa/dsa.yaml b/Documentation/devicetree/bindings/net/dsa/dsa.yaml
>> new file mode 100644
>> index 000000000000..bec257231bf8
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/dsa/dsa.yaml
>> @@ -0,0 +1,80 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/net/dsa/dsa.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Distributed Switch Architecture Device Tree Bindings
> 
> DSA is a Linuxism, right?

Not really, it is a Marvell term that describes their proprietary
switching protocol. Since then DSA within Linux expands well beyond just
Marvell switches, so the terms have been blurred a little bit.

> 
>> +
>> +maintainers:
>> +  - Andrew Lunn <andrew@...n.ch>
>> +  - Florian Fainelli <f.fainelli@...il.com>
>> +  - Vivien Didelot <vivien.didelot@...il.com>
>> +
>> +description:
>> +  Switches are true Linux devices and can be probed by any means. Once probed,
> 
> Bindings are OS independent.
> 
>> +  they register to the DSA framework, passing a node pointer. This node is
>> +  expected to fulfil the following binding, and may contain additional
>> +  properties as required by the device it is embedded within.
> 
> Describe what type of h/w should use this binding.
> 
>> +
>> +properties:
>> +  $nodename:
>> +    pattern: "^switch(@.*)?$"
>> +
>> +  dsa,member:
>> +    minItems: 2
>> +    maxItems: 2
>> +    description:
>> +      A two element list indicates which DSA cluster, and position within the
>> +      cluster a switch takes. <0 0> is cluster 0, switch 0. <0 1> is cluster 0,
>> +      switch 1. <1 0> is cluster 1, switch 0. A switch not part of any cluster
>> +      (single device hanging off a CPU port) must not specify this property
>> +    $ref: /schemas/types.yaml#/definitions/uint32-array
>> +
>> +  ports:
>> +    type: object
>> +    properties:
>> +      '#address-cells':
>> +        const: 1
>> +      '#size-cells':
>> +        const: 0
>> +
>> +    patternProperties:
>> +      "^port@[0-9]+$":
> 
> As ports and port are OF graph nodes, it would be better if we 
> standardized on a different name for these. I think we've used 
> 'ethernet-port' some.

Yes we did talk about that before, however when the original DSA binding
was introduced about 7 years ago (or maybe more recently, my memory
fails me now), "ports" was chosen as the encapsulating node. We should
be accepting both ethernet-ports and ports.

> 
>> +          type: object
>> +          description: DSA switch ports
>> +
>> +          allOf:
>> +            - $ref: ../ethernet-controller.yaml#
> 
> How does this and 'ethernet' both apply?

I think the intent here was to mean that some of the properties from the
Ethernet controller such as phy-mode, phy-handle, fixed-link also apply
here since the switch port is a simplified Ethernet MAC on a number of
counts.
-- 
Florian