linux-kernel - Re: [PATCH net-next v2 1/1] net: mdio: reset PHY before attempting to access ID register

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Message-ID: <aS7gL3md82HEEjaP@shell.armlinux.org.uk>
Date: Tue, 2 Dec 2025 12:48:47 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Buday Csaba <buday.csaba@...lan.hu>, Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 1/1] net: mdio: reset PHY before attempting
 to access ID register

On Tue, Dec 02, 2025 at 01:38:21PM +0100, Paolo Abeni wrote:
> On 11/28/25 2:53 PM, Buday Csaba wrote:
> > When the ID of an Ethernet PHY is not provided by the 'compatible'
> > string in the device tree, its actual ID is read via the MDIO bus.
> > For some PHYs this could be unsafe, since a hard reset may be
> > necessary to safely access the MDIO registers.
> > 
> > Add a fallback mechanism for such devices: when reading the ID
> > fails, the reset will be asserted, and the ID read is retried.
> > 
> > This allows such devices to be used with an autodetected ID.
> > 
> > The fallback mechanism is activated in the error handling path, and
> > the return code of fwnode_mdiobus_register_phy() is unaltered, except
> > when the reset fails with -EPROBE_DEFER, which is propagated to the
> > caller.
> > 
> > Signed-off-by: Buday Csaba <buday.csaba@...lan.hu>
> 
> IMHO this deserves an explicit ack from phy maintainers. Unless such ack
> is going to land on the ML very soon, I suggest to defer this patch to
> the next cycle, as Jakub is wrapping the net-next PR.

No time to do anything quickly, sorry.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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