Re: [RFC PATCH net-next 8/8] dt-bindings: net: fsl,backplane-anlt: new binding document

From: Andrew Lunn <andrew@lunn.ch>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: Rob Herring <robh@kernel.org>,
	netdev@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org,
	"Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Madalin Bucur <madalin.bucur@nxp.com>,
	Ioana Ciornei <ioana.ciornei@nxp.com>,
	Camelia Groza <camelia.groza@nxp.com>,
	Li Yang <leoyang.li@nxp.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor@kernel.org>,
	Sean Anderson <sean.anderson@seco.com>,
	Maxime Chevallier <maxime.chevallier@bootlin.com>,
	Vinod Koul <vkoul@kernel.org>,
	Kishon Vijay Abraham I <kishon@kernel.org>
Subject: Re: [RFC PATCH net-next 8/8] dt-bindings: net: fsl,backplane-anlt: new binding document
Date: Mon, 21 Aug 2023 23:10:27 +0200	[thread overview]
Message-ID: <842f7ff0-d376-4f55-b72d-2db7ea827792@lunn.ch> (raw)
In-Reply-To: <20230821203433.ysulh2bixfypbhsk@skbuf>

> But, there's already something else at those MDIO registers (where the
> standard PHY ID location is), in the MMD that the AN/LT block responds to.
> And that would be:
> 
> /* Auto-Negotiation Control and Status Registers are on page 0: 0x0 */
> static const u16 mtip_lx2160a_an_regs[] = {
> 	[AN_CTRL] = 0,
> 	[AN_STAT] = 1,
> 	[AN_ADV_0] = 2, // overlaps with MII_PHYSID1
> 	[AN_ADV_1] = 3, // overlaps with MII_PHYSID2
> 	[AN_ADV_2] = 4,
> 	[AN_LPA_0] = 5, // overlaps with MDIO_DEVS1
> 	[AN_LPA_1] = 6, // overlaps with MDIO_DEVS2
> 	[AN_LPA_2] = 7,
> 	[AN_MS_CNT] = 8,
> 	[AN_ADV_XNP_0] = 9,
> 	[AN_ADV_XNP_1] = 10,
> 	[AN_ADV_XNP_2] = 11,
> 	[AN_LPA_XNP_0] = 12,
> 	[AN_LPA_XNP_1] = 13,
> 	[AN_LPA_XNP_2] = 14,
> 	[AN_BP_ETH_STAT] = 15,
> };
> 
> The AN advertisement registers are kinda important to the operation of
> the driver, so I wouldn't want to mask them with fake PHY ID values
> reported by the MDIO controller.

O.K, not ideal. For C22, you could just put the ID values in the
compatible, which is enough to get a driver loaded which supports that
ID. But somebody recently commented that that does not work for C45. I
assume NXP has an OUI, and could allocate an ID to this device in
retrospect. So maybe it makes sense to make C45 work with an ID in the
compatible? And get the driver loaded that way?

	Andrew

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