Re: [PATCH] net: mdio: force deassert MDIO reset signal

From: Andrew Lunn <andrew@lunn.ch>
To: Lars-Peter Clausen <lars@metafoo.de>
Cc: Pierluigi Passaro <pierluigi.passaro@gmail.com>,
	hkallweit1@gmail.com, linux@armlinux.org.uk, davem@davemloft.net,
	edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	eran.m@variscite.com, nate.d@variscite.com,
	francesco.f@variscite.com, pierluigi.p@variscite.com
Subject: Re: [PATCH] net: mdio: force deassert MDIO reset signal
Date: Tue, 17 Jan 2023 14:40:39 +0100	[thread overview]
Message-ID: <Y8alV6FUKsN2x2XZ@lunn.ch> (raw)
In-Reply-To: <cc338014-8a2b-87e9-7684-20b57aae4ac3@metafoo.de>

> > So compatible "ethernet-phy-ieee802.3-c45" results in is_c45 being set
> > true. The if (is_c45 || is then true, so it does not need to call
> > fwnode_get_phy_id(child, &phy_id) so ignores whatever ID is in DT and
> > asks the PHY.
> > 
> > Try this, totally untested:
> > 
> > diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
> > index b782c35c4ac1..13be23f8ac97 100644
> > --- a/drivers/net/mdio/fwnode_mdio.c
> > +++ b/drivers/net/mdio/fwnode_mdio.c
> > @@ -134,10 +134,10 @@ int fwnode_mdiobus_register_phy(struct mii_bus *bus,
> >          if (rc >= 0)
> >                  is_c45 = true;
> > -       if (is_c45 || fwnode_get_phy_id(child, &phy_id))
> > +       if (fwnode_get_phy_id (child, &phy_id))
> >                  phy = get_phy_device(bus, addr, is_c45);
> >          else
> > -               phy = phy_device_create(bus, addr, phy_id, 0, NULL);
> > +               phy = phy_device_create(bus, addr, phy_id, is_c45, NULL);
> >          if (IS_ERR(phy)) {
> >                  rc = PTR_ERR(phy);
> >                  goto clean_mii_ts;
> > 
> I think part of the problem is that for C45 there are a few other fields
> that get populated by the ID detection, such as devices_in_package and
> mmds_present. Is this something we can do after running the PHY drivers
> probe function? Or is it too late at that point?

As i hinted, it needs somebody to actually debug this and figure out
why it does not work.

I think what i did above is part of the solution. You need to actually
read the ID from the DT, which if you never call fwnode_get_phy_id()
you never do.

You then need to look at phy_bus_match() and probably remove the

		return 0;
	} else {

so that C22 style ID matching is performed if matching via
c45_ids.device_ids fails.

	Andrew