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 13:42:21 -0500
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>
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 12:34 PM, Florian Fainelli wrote:
> 
> 
> 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.

The link phydev->netdev still can be created. And failure to create links
is non fatal error in my opinion. 

> 
>>
>> 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.
> 

Error still will be reported, just not warning and it will be non-fatal.
So, with this patch set it will be possible now to continue boot (NFS for example),
connect to the system and gather logs.


-- 
regards,
-grygorii