netdev - Re: net: phylink: supported modes set to 0 with genphy sfp module

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Date:   Mon, 11 May 2020 12:06:31 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Julien Beraud <julien.beraud@...lia.com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>
Subject: Re: net: phylink: supported modes set to 0 with genphy sfp module



On 5/11/2020 11:29 AM, Russell King - ARM Linux admin wrote:
> On Mon, May 11, 2020 at 05:45:02PM +0200, Julien Beraud wrote:
>> Following commit:
>>
>> commit 52c956003a9d5bcae1f445f9dfd42b624adb6e87
>> Author: Russell King <rmk+kernel@...linux.org.uk>
>> Date:   Wed Dec 11 10:56:45 2019 +0000
>>
>>     net: phylink: delay MAC configuration for copper SFP modules
>>
>>
>> In function phylink_sfp_connect_phy, phylink_sfp_config is called before
>> phylink_attach_phy.
>>
>> In the case of a genphy, the "supported" field of the phy_device is filled
>> by:
>> phylink_attach_phy->phy_attach_direct->phy_probe->genphy_read_abilities.
>>
>> It means that:
>>
>> ret = phylink_sfp_config(pl, mode, phy->supported, phy->advertising);
>> will have phy->supported with no bits set, and then the first call to
>> phylink_validate in phylink_sfp_config will return an error:
>>
>> return phylink_is_empty_linkmode(supported) ? -EINVAL : 0;
>>
>> this results in putting the sfp driver in "failed" state.
> 
> Which PHY is this?

Using the generic PHY with a copper SFP module does not sound like a
great idea because without a specialized PHY driver (that is, not the
Generic PHY driver) there is not usually much that can happen.
-- 
Florian