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Date:   Tue, 1 Jun 2021 18:47:34 +0800
From:   Wong Vee Khee <vee.khee.wong@linux.intel.com>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC net-next 0/2] Introduce MDIO probe order C45 over C22
Message-ID: <20210601104734.GA18984@linux.intel.com>
References: <20210525055803.22116-1-vee.khee.wong@linux.intel.com>
 <YKz86iMwoP3VT4uh@lunn.ch>
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On Tue, May 25, 2021 at 03:34:34PM +0200, Andrew Lunn wrote:
> On Tue, May 25, 2021 at 01:58:03PM +0800, Wong Vee Khee wrote:
> > Synopsys MAC controller is capable of pairing with external PHY devices
> > that accessible via Clause-22 and Clause-45.
> > 
> > There is a problem when it is paired with Marvell 88E2110 which returns
> > PHY ID of 0 using get_phy_c22_id(). We can add this check in that
> > function, but this will break swphy, as swphy_reg_reg() return 0. [1]
> 
> Is it possible to identify it is a Marvell PHY? Do any of the other
> C22 registers return anything unique? I'm wondering if adding
> .match_phy_device to genphy would work to identify it is a Marvell PHY
> and not bind to it. Or we can turn it around, make the
> .match_phy_device specifically look for the fixed-link device by
> putting a magic number in one of the vendor registers.
>

I checked the Marvell and did not see any unique register values.
Also, since get_phy_c22_id() returns a *phy_id== 0, it is not bind to
any PHY driver, so I don't think adding the match_phy_device check in
getphy would help.

 VK