netdev - RE: [PATCH net] net: phy: add device link between MAC device and MDIO device

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Message-ID:
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Date: Thu, 29 Jan 2026 10:47:32 +0000
From: Wei Fang <wei.fang@....com>
To: Maxime Chevallier <maxime.chevallier@...tlin.com>
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Subject: RE: [PATCH net] net: phy: add device link between MAC device and MDIO
 device

> It is removed :
>
> https://elixir.boo/
> tlin.com%2Flinux%2Fv6.19-rc5%2Fsource%2Fdrivers%2Fnet%2Fphy%2Fsfp.c%2
> 3L2648&data=05%7C02%7Cwei.fang%40nxp.com%7C2f06a252bfa24532562e0
> 8de5f1fbe42%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6390527
> 87105780228%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlY
> iOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C
> 0%7C%7C%7C&sdata=FtbZ%2FZWqje7ckLwHvVENVlkus7nsTB3hZ3N05jYuflc%3
> D&reserved=0
>
> This line above is called when we unplug the SFP module.
>

Many thanks for your detailed explanation, I really know very little
about SFP. :(

> What I am seeing is that there are other devlink links that apply to
> the net_device, unrelated to the MDIO bus, at least on the devices I am
> testing this on, and they prevent the net_device from going away.
>
> One of these devlinks is a link between the sfp cage (compatible "sff,sfp") and
> the netdev. This devlink seems to be automatically populated when OF is
> parsed.
>
> To solve this, I think we need something more granular that this approach,
> and make a distinction between when it's OK for a phy_device to dissapear
> when attached to a MAC (SFP phys), and when it's not (PHYs hardwired to
> the MAC).

Yes, perhaps we need to add some flags to determine whether to add a
devlink between MAC controller and MDIO controller.

>
> Adding this devlink in phy_attach_direct() is too generic IMO. It's likely
> that this link should be populated by phylink then.
>

Some drivers may not use phylink, like the fec driver.