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Date:   Mon, 28 Jun 2021 14:05:26 +0200
From:   Lukasz Majewski <lukma@denx.de>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Madalin Bucur <madalin.bucur@oss.nxp.com>,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        Joakim Zhang <qiangqing.zhang@nxp.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>, netdev@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>,
        Mark Einon <mark.einon@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC 2/3] net: Provide switchdev driver for NXP's More Than IP
 L2 switch
Message-ID: <20210628140526.7417fbf2@ktm>
In-Reply-To: <YNXq1bp7XH8jRyx0@lunn.ch>
References: <20210622144111.19647-1-lukma@denx.de>
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        <YNH7vS9FgvEhz2fZ@lunn.ch>
        <20210623133704.334a84df@ktm>
        <YNOTKl7ZKk8vhcMR@lunn.ch>
        <20210624125304.36636a44@ktm>
        <YNSJyf5vN4YuTUGb@lunn.ch>
        <20210624163542.5b6d87ee@ktm>
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Hi Andrew,

> > I do believe that I can just extend the L2 switch driver (fec_mtip.c
> > file to be precise) to provide full blown L2 switch functionality
> > without touching the legacy FEC more than in this patch set.
> >=20
> > Would you consider applying this patch series then? =20
>=20
> What is most important is the ABI. If something is merged now, we need
> to ensure it does not block later refactoring to a clean new
> driver. The DT binding is considered ABI. So the DT binding needs to
> be like a traditional switchdev driver. Florian already pointed out,
> you can use a binding very similar to DSA. ti,cpsw-switch.yaml is
> another good example.

The best I could get would be:

&eth_switch {
	compatible =3D "imx,mtip-l2switch";
	reg =3D <0x800f8000 0x400>, <0x800fC000 0x4000>;

	interrupts =3D <100>;
	status =3D "okay";

	ethernet-ports {
		port1@1 {
			reg =3D <1>;
			label =3D "eth0";
			phys =3D <&mac0 0>;
		};

		port2@2 {
			reg =3D <2>;
			label =3D "eth1";
			phys =3D <&mac1 1>;
		};
	};
};

Which would abuse the "phys" properties usages - as 'mac[01]' are
referring to ethernet controllers.

On TI SoCs (e.g. am33xx-l4.dtsi) phys refer to some separate driver
responsible for PHY management. On NXP this is integrated with FEC
driver itself.

>=20
> So before considering merging your changes, i would like to see a
> usable binding.
>=20
> I also don't remember seeing support for STP. Without that, your
> network has broadcast storm problems when there are loops. So i would
> like to see the code needed to put ports into blocking, listening,
> learning, and forwarding states.
>=20
> 	  Andrew


Best regards,

Lukasz Majewski

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