Re: [RFC net-next 0/2] Introduce MDIO probe order C45 over C22

From: Wong Vee Khee
Date: Tue Jun 01 2021 - 06:47:44 EST

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.