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

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Message-ID: <0ee8416c-dfa2-21bc-2688-58337bfa1e2a@orolia.com>
Date:   Mon, 11 May 2020 17:45:02 +0200
From:   Julien Beraud <julien.beraud@...lia.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Russell King <linux@...linux.org.uk>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>
Subject: net: phylink: supported modes set to 0 with genphy sfp module

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.

Thanks,
Julien Beraud