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

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Date:	Wed, 21 Oct 2015 14:46:50 -0700
From:	Florian Fainelli <f.fainelli@...il.com>
To:	Nathan Sullivan <nathan.sullivan@...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 21/10/15 12:42, Nathan Sullivan wrote:
> 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.

Good point, thanks for clarifiying that part.
-- 
Florian
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