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

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Hi Andrew,

On 14.08.2023 16:09, Andrew Lunn wrote:
>> Ah okay. I didn't consider the switch architecture where the data interface
>> of the PHY is connected to the switch, and the PHY management interface is
>> connected to the mdio bus that the switch is connected to.
> 
> The generic Linux architecture for PHYs and binding them to a MAC via
> a phandle allows the PHY to be on any MDIO bus anywhere. DSA has some
> additional shortcuts to support 1:1 mapping if the switch has its own
> MDIO bus, without describing it in DT, but this is just in addition to
> the generic code.
> 
>> Not json-schema documentation, don't care about:
>> - ar9331.txt
>> - lan9303.txt
>> - lantiq-gswip.txt
>> - marvell.txt
> 
> The marvell switch can have up to 2 MDIO busses. If i remember
> correctly, there is also one switch which has one MDIO bus per port.

I'm writing the json-schema for Marvell switches. I've checked a few
devicetree source files on Linus's Linux tree, I only see two buses used at
the most. The internal bus and another bus with
marvell,mv88e6xxx-mdio-external. I've never seen a devicetree with
marvell,mv88e6250 though. Could the switch that has one MDIO bus per port
be this one? Also, is every bus of this switch a
marvell,mv88e6xxx-mdio-external bus or, one internal bus and the remaining
are marvell mv88e6xxx-mdio-external buses?

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