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

From: Grygorii Strashko
Date: Thu Dec 21 2017 - 15:18:26 EST

On 12/21/2017 03:21 AM, Andrew Lunn wrote:
> 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.

It will not work.
at least as is.

This is error recovery, which is, per my understanding, signalizing about hw or
configuration issue. What i'm thinking about is - may be it'll be reasonable
to add err message here:
if ((regval & 0xFF) == 0xFF) {
+ dev_err_once(&phydev->,
+ "PHY reset due idle error count maxed out");