netdev - Re: [PATCH net] net: phy: micrel: set soft_reset callback to genphy_soft

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Message-ID: <7fd22c9d-c0b3-688e-1ccf-74408c457daa@ti.com>
Date:   Fri, 11 Jan 2019 16:52:28 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     Tony Lindgren <tony@...mide.com>,
        Heiner Kallweit <hkallweit1@...il.com>
CC:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        David Miller <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net] net: phy: micrel: set soft_reset callback to
 genphy_soft_reset for KSZ9031

On 11/01/19 2:57 AM, Tony Lindgren wrote:
> * Heiner Kallweit <hkallweit1@...il.com> [190110 19:41]:
>> On 10.01.2019 20:24, Florian Fainelli wrote:
>>> On 1/10/19 11:22 AM, Heiner Kallweit wrote:
>>>> So far genphy_soft_reset was used automatically if the PHY driver
>>>> didn't implement the soft_reset callback. This changed with the
>>>> mentioned commit and broke KSZ9031. To fix this configure the
>>>> KSZ9031 PHY driver to use genphy_soft_reset.
>>>>
>>>> Fixes: 6e2d85ec0559 ("net: phy: Stop with excessive soft reset")
>>>> Reported-by: Tony Lindgren <tony@...mide.com>
>>>> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
>>>
>>> Thanks a lot for following up with the people at TI on this. We should
>>> really get a better understanding of what the issue is, and whether
>>> there is a possibly better workaround that could be developed which is
>>> not just as hard as a big hammer software reset. Maybe we can get some
>>> people/contacts at Micrel to help here.
>>>
>> In ksz9031_config_init() quite some settings are done and IMO it's not
>> that unusual that it takes a soft reset for such settings to become
>> effective. But I agree it would be nice if somebody from the PHY vendor
>> could comment on whether a soft reset is actually needed. Not sure who
>> has a contact to Microchip.
> 
> Adding Sekhar to Cc, maybe he has some contacts to ask.

I dont have any direct contacts, but I will ask internally.

> 
>> If the feedback takes time it may be better to apply the soft reset as
>> fix and replace it later in case we have a less intrusive option.
> 
> Yes please let's fix the regression first and then patch
> more later as needed.

+1

I justed tested AM437x GP EVM with 10 times cable plug-unplug and this
fixes the regression.

Tested-by: Sekhar Nori <nsekhar@...com>

Thanks,
Sekhar