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Date: Tue, 26 Dec 2023 19:05:09 +0200
From: Vladimir Oltean <olteanv@gmail.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Jagan Teki <jagan@amarulasolutions.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	"Andrew F. Davis" <afd@ti.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	linux-kernel <linux-kernel@vger.kernel.org>, netdev@vger.kernel.org,
	Michael Nazzareno Trimarchi <michael@amarulasolutions.com>,
	Ioana Ciornei <ioana.ciornei@nxp.com>,
	Shawn Guo <shawnguo@kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Fabio Estevam <festevam@gmail.com>
Subject: Re: PHY issue with SJA1105Q/DP84849I Design
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On Tue, Dec 26, 2023 at 06:00:17PM +0100, Andrew Lunn wrote:
> > The code which should have prevented this from happening is in
> > phy_attach_direct():
> > 
> > 	if (phydev->attached_dev) {
> > 		dev_err(&dev->dev, "PHY already attached\n");
> > 		err = -EBUSY;
> > 		goto error;
> > 	}
> 
> The problem might be dsa_shared_port_phylink_register():
> 
>         err = phylink_of_phy_connect(dp->pl, port_dn, 0);
>         if (err && err != -ENODEV) {
>                 pr_err("could not attach to PHY: %d\n", err);
>                 goto err_phy_connect;
>         }
> 
>         return 0;
> 
> Since it is not -ENODEV, it just keep going.
> 
>       Andrew

"Shared" ports are DSA and CPU ports, the report is on a user port.
There, if phylink_of_phy_connect() fails, we try dsa_user_phy_connect(),
but only if the driver provides a ds->user_mii_bus, which sja1105 does not.
So the failure should be nice and clean. It might be worth posting a
full boot log though, since this is really strange.