linux-kernel - Re: [PATCH 0/2] net: phy: relax error checking when creating sysfs link netdev->phydev

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Date:   Fri, 16 Mar 2018 10:34:35 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Grygorii Strashko <grygorii.strashko@...com>
Cc:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sekhar Nori <nsekhar@...com>, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org
Subject: Re: [PATCH 0/2] net: phy: relax error checking when creating sysfs
 link netdev->phydev



On 03/16/2018 10:22 AM, Andrew Lunn wrote:
> On Wed, Mar 14, 2018 at 05:26:22PM -0500, Grygorii Strashko wrote:
>> Some ethernet drivers (like TI CPSW) may connect and manage >1 Net PHYs per
>> one netdevice, as result such drivers will produce warning during system
>> boot and fail to connect second phy to netdevice when PHYLIB framework
>> will try to create sysfs link netdev->phydev for second PHY
>> in phy_attach_direct(), because sysfs link with the same name has been
>> created already for the first PHY.
>> As result, second CPSW external port will became unusable.
>> This issue was introduced by commits:
>> 5568363f0cb3 ("net: phy: Create sysfs reciprocal links for attached_dev/phydev"
>> a3995460491d ("net: phy: Relax error checking on sysfs_create_link()"
> 
> I wonder if it would be better to add a flag to the phydev that
> indicates it is the second PHY connected to a MAC? Add a bit to
> phydrv->mdiodrv.flags. If that bit is set, don't create the sysfs
> file.

We could indeed do that, I am fine with Grygorii's approach though in
making the creation more silent and non fatal.

> 
> For 99% of MAC drivers, having two PHYs is an error, so we want to aid
> debug by reporting the sysfs error.
That is true, either way is fine with me, really.
-- 
Florian