Re: [PATCH 2/2] dt-bindings: net: dsa: mediatek,mt7530: document MDIO-bus

From: Andrew Lunn <andrew@lunn.ch>
To: "Arınç ÜNAL" <arinc.unal@arinc9.com>
Cc: David Bauer <mail@david-bauer.net>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Vladimir Oltean <olteanv@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	AngeloGioacchino Del Regno
	<angelogioacchino.delregno@collabora.com>,
	Landen Chao <Landen.Chao@mediatek.com>,
	DENG Qingfang <dqfext@gmail.com>,
	Sean Wang <sean.wang@mediatek.com>,
	Daniel Golle <daniel@makrotopia.org>,
	netdev@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH 2/2] dt-bindings: net: dsa: mediatek,mt7530: document MDIO-bus
Date: Sun, 30 Apr 2023 20:48:37 +0200	[thread overview]
Message-ID: <207753d6-cffd-4a23-be16-658d7c9ceb4a@lunn.ch> (raw)
In-Reply-To: <a6c6fe83-fbb5-f289-2210-6f1db6585636@arinc9.com>

> > Try setting ds->slave_mii_bus to the MDIO bus you register via
> > of_mdiobus_register().
> 
> That seems to be the case already, under mt7530_setup_mdio():
> 
> 	bus = devm_mdiobus_alloc(dev);
> 	if (!bus)
> 		return -ENOMEM;
> 
> 	ds->slave_mii_bus = bus;
> 
> The bus is registered with devm_of_mdiobus_register(), if that matters. (My
> current knowledge about OF or OF helpers for MDIO is next to nothing.)
> 
> The same behaviour is there.

Maybe take a look at what is going on in dsa_slave_phy_setup() and
dsa_slave_phy_connect().

The way i understand it, is it first looks in DT to see if there is a
phy-handle, and if there is, it uses it. If not, it assumes there is a
1:1 mapping between port number and PHY address, and looks to see if a
PHY has been found on ds->slave_mii_bus at that address, and uses it.

So i don't think you need to list the PHY, the fallback should be
used.

	Andrew

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