netdev - Re: [PATCH] net: phy: micrel: ksz9031: reconfigure autoneg after phy autoneg workaround

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Message-ID: <20171221092112.GD6683@lunn.ch>
Date:   Thu, 21 Dec 2017 10:21:12 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Grygorii Strashko <grygorii.strashko@...com>
Cc:     Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Sekhar Nori <nsekhar@...com>
Subject: Re: [PATCH] net: phy: micrel: ksz9031: reconfigure autoneg after phy
 autoneg workaround

On Wed, Dec 20, 2017 at 06:45:10PM -0600, Grygorii Strashko wrote:
> Under some circumstances driver will perform PHY reset in
> ksz9031_read_status() to fix autoneg failure case (idle error count =
> 0xFF). When this happens ksz9031 will not detect link status change any
> more when connecting to Netgear 1G switch (link can be recovered sometimes by
> restarting netdevice "ifconfig down up"). Reproduced with TI am572x board
> equipped with ksz9031 PHY while connecting to Netgear 1G switch.
> 
> Fix the issue by reconfiguring autonegotiation after PHY reset in
> ksz9031_read_status().

Hi Grygorii

I can understand the fix.

But i'm wondering if there is a better way to do this. Can you call
phy_stop() and phy_start(). You then get the core phy code doing the
same initialisation as what happened the first time. However, i know
this is not easy. _read_status() is being called from the middle of
the state machine, and trying to change the state of the state machine
at this point is problematic.

   Andrew