netdev - Re: [PATCH net-next] net: dsa: mt7530: register OF node for internal MDIO bus

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Message-ID: <8e248f59-007a-4c53-877f-6026f4a74d0b@lunn.ch>
Date: Thu, 21 Dec 2023 10:27:24 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Ravi Gunasekaran <r-gunasekaran@...com>
Cc: Arınç ÜNAL <arinc.unal@...nc9.com>,
	Daniel Golle <daniel@...rotopia.org>,
	Landen Chao <Landen.Chao@...iatek.com>,
	DENG Qingfang <dqfext@...il.com>,
	Sean Wang <sean.wang@...iatek.com>,
	Florian Fainelli <f.fainelli@...il.com>,
	Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	David Bauer <mail@...id-bauer.net>, mithat.guner@...ont.com,
	erkin.bozoglu@...ont.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net-next] net: dsa: mt7530: register OF node for internal
 MDIO bus

> > @@ -2177,7 +2180,9 @@ mt7530_setup_mdio(struct mt7530_priv *priv)
> >  	if (priv->irq)
> >  		mt7530_setup_mdio_irq(priv);
> >  
> > -	ret = devm_mdiobus_register(dev, bus);
> > +	mnp = of_get_child_by_name(np, "mdio");
> 
> If the node is not found, then the return value would be NULL.
> Though devm_of_mdiobus_register() and of_node_put() take care of NULL references,
> other drivers that use devm_of_mdiobus_register() mostly perform a early exit if the node is NULL.

Actually, many don't as well. of_mdiobus_register() falls back to
mdiobus_register() is np==NULL. That causes a scan of the bus to find
all the PHYs and you can then use phy_find_first() to access them.

So this code is O.K.

   Andrew