netdev - Re: Regression in v4.20 with net phy soft reset changes

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Date:   Thu, 10 Jan 2019 11:20:10 +0530
From:   Keerthy <j-keerthy@...com>
To:     Tony Lindgren <tony@...mide.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Sekhar Nori <nsekhar@...com>
CC:     Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Andrew Lunn <andrew@...n.ch>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Chris Healy <cphealy@...il.com>,
        Clemens Gruber <clemens.gruber@...ruber.com>,
        Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>,
        Murali Karicheri <m-karicheri2@...com>,
        Rex Chang <rchang@...com>, Tero Kristo <t-kristo@...com>,
        WingMan Kwok <w-kwok2@...com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-omap@...r.kernel.org>
Subject: Re: Regression in v4.20 with net phy soft reset changes



On Thursday 10 January 2019 10:36 AM, Keerthy wrote:
> 
> 
> On Thursday 10 January 2019 03:06 AM, Tony Lindgren wrote:
>> Hi,
>>
>> * Heiner Kallweit <hkallweit1@...il.com> [190109 19:28]:
>>> On 09.01.2019 20:06, Tony Lindgren wrote:
>>>> Commit 6e2d85ec0559 ("net: phy: Stop with excessive soft reset") caused
>>>> a regression where suspend resume cycle fails to bring up Ethernet on at
>>>> least cpsw on am437x-sk-evm.
>>>>
>>> What kind of PHY and which PHY driver is used with this board?
>>> I found one schematics of am437x where a KSZ9031RN PHY is used.
>>> Is it the same on your board?
>>
>> Yes that's the phy.
>>
>>> As described in the commit message of this commit you would have
>>> the option to implement the soft_reset callback in the PHY driver.
>>> Can you try to add .soft_reset = genphy_soft_reset to the
>>> KSZ9031 driver config in drivers/net/phy/micrel.c and check whether
>>> it fixes the issue?
>>
>> Yes that seems to work based on a quick test of five suspend
>> resume cycles.
> 

Removing Grygorii as the e-mail no longer exists

To add to Tony's observations. I ran a 100 time suspend/resume adding the
soft_reset hook to the phy_driver structs in drivers/net/phy/micrel.c and
suspend/resume (DS0) works nicely.

> 
>>
>> I wonder what all hardware this issue affects though?
>>
>> It's probably best that the network folks check what all
>> hardare needs patching.
>>
>> For TI hardware, Sekhar and TI network folks, can you guys
>> please check the various TI SoCs for multiple suspend resume
>> cycles with v5.0-rc1 and patch accordingly? See also below
>> for something else to check, 10 seconds to resume a phy
>> seems very long to me :)
>>
>>>> Keerthy noticed this may not happen on the first resume, but usually
>>>> happens after few suspend resume cycles. The most working suspend resume
>>>> cycles I've seen with the commit above is three.
>> ...
>>>> Note that unrelated to the commit above, there may be other issues too
>>>> as the cpsw phy LED seems to come on only after about five seconds with
>>>> about total of 10 seconds before the Ethernet is up again.
>>
>> Regards,
>>
>> Tony
>>