netdev - RE: [RFC net-next 2/5] net: phylink: add separate pcs operations structure

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Date:   Tue, 17 Mar 2020 16:04:28 +0000
From:   Jose Abreu <Jose.Abreu@...opsys.com>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
CC:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [RFC net-next 2/5] net: phylink: add separate pcs operations
 structure

From: Russell King - ARM Linux admin <linux@...linux.org.uk>
Date: Mar/17/2020, 15:56:10 (UTC+00:00)

> > Please consider removing this condition and just rely on an_enabled field. 
> > I have USXGMII support for Clause 73 Autoneg so this won't work with 
> > that.
> 
> That is actually incorrect.  SGMII can have an_enabled being true, but
> SGMII is not an autonegotiation between the MAC and PHY - it is merely
> a mechanism for the PHY to inform the MAC what the results of _its_
> negotiation are.
> 
> I suspect USXGMII is the same since it is just an "upgraded" version of
> SGMII.  Please can you check whether there really is any value in trying
> (and likely failing) to restart the "handshake" with the PHY from the
> MAC end, rather than requesting the PHY to restart negotiation on its
> media side.

I think we are speaking of different things here. I'm speaking about 
end-to-end Autoneg. Not PHY <-> PCS <-> MAC.

I'm so sorry but I'm not an expert in this field, I just deal mostly with 
IP.

Anyway, I'm speaking about end-to-end Clause 73 Autoneg which involves 
exchanging info with the peer. If peer for some reason is not available to 
receive this info then AutoNeg will not succeed. Hence the reason to 
restart it.

---
Thanks,
Jose Miguel Abreu