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

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Date:   Wed, 9 Jan 2019 20:28:21 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Tony Lindgren <tony@...mide.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Chris Healy <cphealy@...il.com>,
        Clemens Gruber <clemens.gruber@...ruber.com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>,
        Keerthy <j-keerthy@...com>,
        Murali Karicheri <m-karicheri2@...com>,
        Rex Chang <rchang@...com>, Sekhar Nori <nsekhar@...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 09.01.2019 20:06, Tony Lindgren wrote:
> Hi all,
> 
> 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?

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?

> 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.
> 
> Any ideas what might be going wrong?
> 
> 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
> 
Heiner