[PATCH 2/2] net: phy: atheros: avoid error in ar803x_of_init() when PHY has no OF node

[Ramon Fried]

On Thu, Mar 3, 2022 at 9:53 AM Ramon Fried <rfried.dev at gmail.com> wrote:
>
> On Wed, Feb 23, 2022 at 3:21 PM Vladimir Oltean <vladimir.oltean at nxp.com> wrote:
> >
> > A DM_ETH driver may use phy_connect() towards a PHY address on an MDIO
> > bus which is not specified in the device tree, as evidenced by:
> >
> > pfe_eth_probe
> > -> pfe_phy_configure
> >    -> phy_connect
> >
> > When this happens, the PHY will have an invalid OF node.
> >
> > When ar803x_config() runs, it silently fails at ar803x_of_init(), and
> > therefore, fails to run the rest of the initialization.
> >
> > This makes MII_BMCR contain what it had after BMCR_RESET (0x8000) has
> > been written into it by phy_reset(). Since BMCR_RESET is volatile and
> > self-clearing, the MII_BMCR ends up having a value of 0x0. The further
> > configuration of this register, which is supposed to be handled by
> > genphy_config_aneg() lower in ar803x_config(), never gets a chance to
> > run due to this early error from ar803x_of_init().
> >
> > As a result of having MII_BMCR as 0, the following symptom appears:
> >
> > => setenv ethact pfe_eth0
> > => setenv ipaddr 10.0.0.1
> > => ping 10.0.0.2
> > pfe_eth0 Waiting for PHY auto negotiation to complete......... TIMEOUT !
> > Could not initialize PHY pfe_eth0
> >
> > Manually writing 0x1140 into register 0 of the PHY makes the connection
> > work, but it is rather desirable that the port works without any manual
> > intervention.
> >
> > Fixes: fe6293a80959 ("phy: atheros: add device tree bindings and config")
> > Signed-off-by: Vladimir Oltean <vladimir.oltean at nxp.com>
> > ---
> >  drivers/net/phy/atheros.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/phy/atheros.c b/drivers/net/phy/atheros.c
> > index f922fecd6b5d..fa1fe08518f4 100644
> > --- a/drivers/net/phy/atheros.c
> > +++ b/drivers/net/phy/atheros.c
> > @@ -199,7 +199,7 @@ static int ar803x_of_init(struct phy_device *phydev)
> >
> >         node = phy_get_ofnode(phydev);
> >         if (!ofnode_valid(node))
> > -               return -EINVAL;
> > +               return 0;
> >
> >         priv = malloc(sizeof(*priv));
> >         if (!priv)
> > --
> > 2.25.1
> >
> Reviewed-by: Ramon Fried <rfried.dev at gmail.com>
Applied to u-boot-net/next
Thanks,
Ramon