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	Mon, 02 Feb 2026 18:09:22 +0000
Date: Mon, 2 Feb 2026 18:09:17 +0000
From: Daniel Golle <daniel@makrotopia.org>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>, "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	Simon Horman <horms@kernel.org>, netdev@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	Frank Wunderlich <frankwu@gmx.de>, Chad Monroe <chad@monroe.io>,
	Cezary Wilmanski <cezary.wilmanski@adtran.com>,
	Avinash Jayaraman <ajayaraman@maxlinear.com>,
	Bing tao Xu <bxu@maxlinear.com>, Liang Xu <lxu@maxlinear.com>,
	Juraj Povazanec <jpovazanec@maxlinear.com>,
	"Fanni (Fang-Yi) Chan" <fchan@maxlinear.com>,
	"Benny (Ying-Tsan) Weng" <yweng@maxlinear.com>,
	"Livia M. Rosu" <lrosu@maxlinear.com>,
	John Crispin <john@phrozen.org>
Subject: Re: [PATCH v12 4/4] net: dsa: add basic initial driver for MxL862xx
 switches
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References: <cover.1769908155.git.daniel@makrotopia.org>
 <c5895811389aed7f426ed9c9461e8ac0e8017da1.1769908155.git.daniel@makrotopia.org>
 <20260202102326.vz5qhg6wzzje553v@skbuf>
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In-Reply-To: <20260202102326.vz5qhg6wzzje553v@skbuf>

On Mon, Feb 02, 2026 at 12:23:26PM +0200, Vladimir Oltean wrote:
> On Sun, Feb 01, 2026 at 02:25:13AM +0000, Daniel Golle wrote:
> > +static int mxl862xx_setup_mdio(struct dsa_switch *ds)
> > +{
> > +	struct mxl862xx_priv *priv = ds->priv;
> > +	struct device *dev = ds->dev;
> > +	struct device_node *mdio_np;
> > +	struct mii_bus *bus;
> > +	int ret;
> > +
> > +	bus = devm_mdiobus_alloc(dev);
> > +	if (!bus)
> > +		return -ENOMEM;
> > +
> > +	bus->priv = priv;
> > +	ds->user_mii_bus = bus;
> > +	bus->name = KBUILD_MODNAME "-mii";
> > +	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-mii", dev_name(dev));
> > +	bus->read_c45 = mxl862xx_phy_read_c45_mii_bus;
> > +	bus->write_c45 = mxl862xx_phy_write_c45_mii_bus;
> > +	bus->read = mxl862xx_phy_read_mii_bus;
> > +	bus->write = mxl862xx_phy_write_mii_bus;
> > +	bus->parent = dev;
> > +	bus->phy_mask = ~ds->phys_mii_mask;
> > +
> > +	mdio_np = of_get_child_by_name(dev->of_node, "mdio");
> > +	if (!mdio_np)
> > +		return -ENODEV;
> 
> As per the dt-bindings patch, the "mdio" child node is not required.
> But here it is.

Now that ports are counted from 0, and 0 being the microcontroller, the
port number no longer matches the PHY ID, so I suppose I got to change
the dt-bindigns as that kinda makes the mdio node mandatory for anything
to work.

> 
> All user ports are given a valid non-NULL dp->cpu_dp pointer. I strongly
> oppose introducing FUD in the code. If there are valid reasons behind
> this I'm all ears, but there aren't.
> 

Looking at other drivers I thought that, and regret not having challenged the
AI commenting on this...