linux-kernel - Re: [PATCH 2/4] dt-bindings: net: dsa: document internal MDIO bus

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Message-ID: <89c9b84c-574c-4071-9524-9207597a3f0a@arinc9.com>
Date:   Wed, 13 Sep 2023 13:59:17 +0300
From:   Arınç ÜNAL <arinc.unal@...nc9.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com,
        Linus Walleij <linus.walleij@...aro.org>,
        Alvin Šipraga <alsi@...g-olufsen.dk>,
        Daniel Golle <daniel@...rotopia.org>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, mithat.guner@...ont.com,
        erkin.bozoglu@...ont.com, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 2/4] dt-bindings: net: dsa: document internal MDIO bus

On 13.09.2023 10:42, Vladimir Oltean wrote:
> On Wed, Sep 13, 2023 at 08:52:37AM +0300, Arınç ÜNAL wrote:
>> On 12.09.2023 22:34, Vladimir Oltean wrote:
>>> Right, it should have been anyOf and not oneOf.. my mistake. It is a bug
>>> which should be fixed. It's the same phylink that gets used in both cases,
>>> user ports and shared ports :)
>>
>> One more thing, I don't recall phy-mode being required to be defined for
>> user ports as it will default to GMII. I don't believe this is the same
>> case for shared ports so phy-mode is required only for them?
> 
> phy-mode is not strictly required, but I think there is a strong
> preference to set it. IIRC, when looking at the DSA device trees, there
> was no case where phy-mode would be absent on CPU/DSA ports if the other
> link properties were also present, so we required it too. There were no
> complaints in 1 year since dsa_shared_port_validate_of() is there. The
> requirement can be relaxed to just a warning and no error in the kernel,
> and the removal of "required" in the schema, if it helps making it
> common with user ports.

I'd say no need as it doesn't make it complicated that much. See below.

> 
> I think that the fallback to PHY_INTERFACE_MODE_GMII applies only if
> there is a phy_device (phy-handle). But otherwise, I don't remember if
> the PHY_INTERFACE_MODE_NA passed to phylink_create() will persist at
> runtime, or cause an error somewhere.
> 
>>>> The phylink bindings for shared ports enforced on all switches on
>>>> dsa-port.yaml:
>>>>
>>>>     allOf:
>>>>       - required:
>>>>           - phy-mode
>>>>       - oneOf:
>>>>           - required:
>>>>               - fixed-link
>>>>           - required:
>>>>               - phy-handle
>>>>           - required:
>>>>               - managed
>>>>
>>>> Here's what I understand:
>>>>
>>>> - For switches in dsa_switches_apply_workarounds[]
>>>>     - Enforce the latter for shared ports.
>>>>     - Enforce the former for user ports.
>>>>
>>>> - For switches not in dsa_switches_apply_workarounds[]
>>>>     - Enforce the former for all ports.
>>>
>>> No, no. We enforce the dt-schema regardless of switch presence in
>>> dsa_switches_apply_workarounds[], to encourage users to fix device trees
>>> (those who run schema validation). The kernel workaround consists in
>>> doing something (skipping phylink) for the device trees where the schema
>>> warns on shared ports. But there should be a single sub-schema for
>>> validating phylink bindings, whatever port kind it is.
>>
>> Hmm, like writing phylink.yaml and then referring to it under the port
>> pattern node? This could prevent a lot of repetition.
>>
>> Arınç
> 
> Yes, that would sound good.

If I understand correctly, these phylink rules are for switch ports. The
fixed-link, phy-handle, and managed properties are described on
ethernet-controller.yaml so I thought it would make sense to define the
rules there and refer to them where they're needed.

Example:

diff --git a/Documentation/devicetree/bindings/net/dsa/dsa-port.yaml b/Documentation/devicetree/bindings/net/dsa/dsa-port.yaml
index 480120469953..7279ab31aea7 100644
--- a/Documentation/devicetree/bindings/net/dsa/dsa-port.yaml
+++ b/Documentation/devicetree/bindings/net/dsa/dsa-port.yaml
@@ -65,16 +65,8 @@ if:
      - required: [ ethernet ]
      - required: [ link ]
  then:
-  allOf:
-    - required:
-        - phy-mode
-    - oneOf:
-        - required:
-            - fixed-link
-        - required:
-            - phy-handle
-        - required:
-            - managed
+  $ref: /schemas/net/ethernet-controller.yaml#/$defs/phylink-switch
+  required: [ phy-mode ]
  
  additionalProperties: true
  
diff --git a/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml b/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
index e532c6b795f4..742aaf1a5ef2 100644
--- a/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
+++ b/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
@@ -179,6 +179,15 @@ required:
    - compatible
    - reg
  
+if:
+  required: [ mdio ]
+then:
+  patternProperties:
+    "^(ethernet-)?ports$":
+      patternProperties:
+        "^(ethernet-)?port@[0-9]+$":
+          $ref: /schemas/net/ethernet-controller.yaml#/$defs/phylink-switch
+
  $defs:
    mt7530-dsa-port:
      patternProperties:
diff --git a/Documentation/devicetree/bindings/net/ethernet-controller.yaml b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
index 9f6a5ccbcefe..d7256f33d946 100644
--- a/Documentation/devicetree/bindings/net/ethernet-controller.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
@@ -284,6 +284,21 @@ allOf:
              controllers that have configurable TX internal delays. If this
              property is present then the MAC applies the TX delay.
  
+$defs:
+  phylink-switch:
+    description: phylink bindings for switch ports
+    allOf:
+      - anyOf:
+          - required: [ fixed-link ]
+          - required: [ phy-handle ]
+          - required: [ managed ]
+
+      - if:
+          required: [ fixed-link ]
+        then:
+          not:
+            required: [ managed ]
+
  additionalProperties: true
  
  ...

Arınç