netdev - Re: [RESEND,net-next] mdio: Make use of bus callbacks

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Message-ID: <4ltztdbct4ce6elmnn7wx5fzh4lywlfbjrn75pdju7cdsw4q2j@ubq7qaa4regr>
Date: Mon, 19 Jan 2026 10:40:32 +0100
From: Uwe Kleine-König <u.kleine-koenig@...libre.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org, andrew@...n.ch, davem@...emloft.net, 
	edumazet@...gle.com, linux@...linux.org.uk, hkallweit1@...il.com, pabeni@...hat.com
Subject: Re: [RESEND,net-next] mdio: Make use of bus callbacks

Hello Jakub,

On Sat, Jan 17, 2026 at 03:29:32PM -0800, Jakub Kicinski wrote:
> Does adding these bus-level callbacks break PHY device probing?
> 
> PHY drivers register via phy_driver_register() which sets:
> 
>     new_driver->mdiodrv.driver.probe = phy_probe;
>     new_driver->mdiodrv.driver.remove = phy_remove;
> 
> The driver core in call_driver_probe() prioritizes bus callbacks over driver
> callbacks:
> 
>     if (dev->bus->probe)
>         ret = dev->bus->probe(dev);
>     else if (drv->probe)
>         ret = drv->probe(dev);
> 
> With mdio_bus_type.probe now set, phy_probe() will never be called for PHY
> devices. The same applies to phy_remove() being bypassed by mdio_bus_remove().
> 
> phy_probe() performs essential initialization including setting phydev->drv,
> reading PHY abilities, configuring EEE, and setting up the state machine.
> Without this, PHY devices would fail to initialize properly.
> 
> Was there a plan to update phy_driver_register() as part of this change, or
> is a separate patch needed to handle PHY drivers?

I think the concern is valid. I'll look into this and send an update
when I convinced myself that I'm not breaking anything.

Best regards
Uwe

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