linux-kernel - Re: [PATCH] net/phy: micrel: Add workaround for bad autoneg

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Message-ID: <20151021194234.GA5746@nathan3500-linux-VM>
Date:	Wed, 21 Oct 2015 14:42:34 -0500
From:	Nathan Sullivan <nathan.sullivan@...com>
To:	Florian Fainelli <f.fainelli@...il.com>
Cc:	netdev <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net/phy: micrel: Add workaround for bad autoneg

On Wed, Oct 21, 2015 at 12:20:21PM -0700, Florian Fainelli wrote:
> 2015-10-21 12:17 GMT-07:00 Nathan Sullivan <nathan.sullivan@...com>:
> > Very rarely, the KSZ9031 will appear to complete autonegotiation, but
> > will drop all traffic afterwards.  When this happens, the idle error
> > count will read 0xFF after autonegotiation completes.  Reset the PHY
> > when in that state.
> >
> > Signed-off-by: Nathan Sullivan <nathan.sullivan@...com>
> > ---
> >  drivers/net/phy/micrel.c |   23 ++++++++++++++++++++++-
> >  1 file changed, 22 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> > index 499185e..cf6312f 100644
> > --- a/drivers/net/phy/micrel.c
> > +++ b/drivers/net/phy/micrel.c
> > @@ -514,6 +514,27 @@ static int ksz8873mll_read_status(struct phy_device *phydev)
> >         return 0;
> >  }
> >
> > +static int ksz9031_read_status(struct phy_device *phydev)
> > +{
> > +       int err;
> > +       int regval;
> > +
> > +       err = genphy_read_status(phydev);
> > +       if (err)
> > +               return err;
> > +
> > +       /* Make sure the PHY is not broken. Read idle error count,
> > +        * and reset the PHY if it is maxed out.
> > +        */
> > +       regval = phy_read(phydev, MII_STAT1000);
> > +       if ((regval & 0xFF) == 0xFF) {
> 
> Don't you also need to set phydev->state to PHY_READY here to force
> the state machine to restart?
>

I don't think so, we stay in the PHY_AN state since phy_init_hw will restart
autonegotiation.  Setting link=0 will go through PHY_NOLINK then back to
PHY_AN, so we wait for autoneg to complete again.

> > +               phy_init_hw(phydev);
> > +               phydev->link = 0;
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> >  static int ksz8873mll_config_aneg(struct phy_device *phydev)
> >  {
> >         return 0;
> > @@ -772,7 +793,7 @@ static struct phy_driver ksphy_driver[] = {
> >         .driver_data    = &ksz9021_type,
> >         .config_init    = ksz9031_config_init,
> >         .config_aneg    = genphy_config_aneg,
> > -       .read_status    = genphy_read_status,
> > +       .read_status    = ksz9031_read_status,
> >         .ack_interrupt  = kszphy_ack_interrupt,
> >         .config_intr    = kszphy_config_intr,
> >         .suspend        = genphy_suspend,
> > --
> > 1.7.10.4
> >
> 
> 
> 
> -- 
> Florian
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