netdev - Re: [PATCH net-next] net: phy: make PHY fixup support always built-in

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Message-ID: <66f110ca-3a49-46fe-a996-c5ad477b8f4d@gmail.com>
Date: Fri, 23 Jan 2026 12:39:22 +0100
From: Heiner Kallweit <hkallweit1@...il.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: Andrew Lunn <andrew@...n.ch>, Paolo Abeni <pabeni@...hat.com>,
 Jakub Kicinski <kuba@...nel.org>, David Miller <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] net: phy: make PHY fixup support always built-in

On 1/23/2026 10:22 AM, Russell King (Oracle) wrote:
> On Fri, Jan 23, 2026 at 07:50:20AM +0100, Heiner Kallweit wrote:
>> PHY fixup registration is used from platform code in init phase only.
>> Let's move the PHY fixup code from the modular part of phylib to the
>> always built-in part of phylib. This allows to annotate the fixup
>> registration as __init.
>>
>> phy_needs_fixup() and phy_scan_fixups() wouldn't have to be moved to
>> the built-in part of phylib. But doing so allows to fully factor out
>> fixup support into its own source code file, and make struct
>> phy_fixup and phy_fixup_list strictly private to phy_fixup.c.
>>
>> phy_scan_fixups() is used after init phase only, then phy_fixup_list
>> is read-only. So we don't need the mutex when accessing the list.
>> Also when registering PHY fixups the mutex isn't needed, because
>> fixup registration is done sequentially from platform init code.
>> Actually there is only one platform with more than one fixup.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
> 
> What is broken today that needs this change, and why haven't we had
> reports of breakage?
> 
Nothing is broken, otherwise patch would have been addressed to net tree.

Recent removal of the dnet driver removed last fixup user not being
platform init code. This (and considering that PHY fixups are a legacy
functionality) allows to:
- factor out this legacy functionality from phy_device.c
- discard half the related code after init phase
- simplify the code (e.g. remove mutex)
- use modular phylib on platforms where fixup just sets a flag,
  e.g. apx4devkit_phy_fixup() in arch/arm/mach-mxs/mach-mxs.c.