linux-kernel - RE: [PATCH net V2 1/1] net: phy: fix invalid phy id when probe using C22

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Message-ID: <BYAPR11MB28702033C50FCB9EAE5686A0AB659@BYAPR11MB2870.namprd11.prod.outlook.com>
Date:   Mon, 22 Mar 2021 12:39:58 +0000
From:   "Wong, Vee Khee" <vee.khee.wong@...el.com>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Heiner Kallweit <hkallweit1@...il.com>
CC:     Andrew Lunn <andrew@...n.ch>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jeremy Linton <jeremy.linton@....com>,
        Calvin Johnson <calvin.johnson@....nxp.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "Voon, Weifeng" <weifeng.voon@...el.com>,
        "Ong, Boon Leong" <boon.leong.ong@...el.com>
Subject: RE: [PATCH net V2 1/1] net: phy: fix invalid phy id when probe using
 C22

On Fri, Mar 19, 2021 at 04:56PM +0800, Russell King - ARM Linux admin wrote:
> On Fri, Mar 19, 2021 at 08:40:45AM +0100, Heiner Kallweit wrote:
>> Is there a specific reason why c22 is probed first? Reversing the order
>> would solve the issue we speak about here.
>> c45-probing of c22-only PHY's shouldn't return false positives
>> (at least at a first glance).
> 
> That would likely cause problems for the I2f MDIO driver, since a
> C45 read is indistinguishable from a C22 write on the I2C bus.
> 

Hi Russell,

STMMAC is capable of supporting external PHYs that accessible using 
C22 or C45. 

Accordng to patch [1] send earlier, it should solve the problem.

As for any other drivers, if it is not using MDIOBUS_C45_C22, 
It should still work as it is by using MDIOBUS_C22.

[1] https://lkml.org/lkml/2020/11/9/443

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