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Date:   Tue, 21 Nov 2023 07:42:44 -0700
From:   Rob Herring <robh@kernel.org>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Christian Marangi <ansuelsmth@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
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        Conor Dooley <conor+dt@kernel.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
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        Russell King <linux@armlinux.org.uk>,
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Subject: Re: [net-next RFC PATCH 03/14] dt-bindings: net: document ethernet
 PHY package nodes
Message-ID: <20231121144244.GA1682395-robh@kernel.org>
References: <20231120135041.15259-1-ansuelsmth@gmail.com>
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On Mon, Nov 20, 2023 at 09:44:58PM +0100, Andrew Lunn 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.
> 
> I think you are being overly narrow here. The 'global' registers could
> be spread over multiple addresses. Particularly for a C22 PHY. I
> suppose they could even be in a N+1 address space, where there is no
> PHY at all.
> 
> Where the global registers are is specific to a PHY package
> vendor/model.

For this reason in particular, the package needs a specific compatible.

> The PHY driver should know this. All the PHY driver
> needs to know is some sort of base offset. PHY0 in this package is
> using address X. It can then use relative addressing from this base to
> access the global registers for this package.
>  
> > 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.
> 
> I don't think it is what simple. See the QCA8084 for example. 3 of the
> 4 PHYs must use QXGMII. The fourth PHY can also use QXGMII but it can
> be multiplexed to a different PMA and use 1000BaseX, SGMII or
> 2500BaseX.
> 
> I do think we need somewhere to put package properties. But i don't
> think phy-mode is such a property. At the moment, i don't have a good
> example of a package property.

What about power supplies and reset/enable lines?

Rob