netdev - Re: phylink / mv8e6xxx and SGMII aneg not working, link doesn't come up

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Date:   Wed, 27 Feb 2019 23:27:41 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: phylink / mv8e6xxx and SGMII aneg not working, link doesn't come
 up

On Thu, Feb 28, 2019 at 12:19:40AM +0100, Andrew Lunn wrote:
> > >From what you've described, it sounds like what you actually have is:
> > 
> > 	MAC <---> Serdes PHY <---> PHY
> > 
> > The Serdes PHY receives the SGMII in-band negotiation from the external
> > PHY, but there is no propagation of the status from the serdes PHY to
> > the MAC.
> 
> Yes, that is a good description. So far, we have not yet got the MAC
> to read the speed and duplex from the SERDES to configure itself. In
> theory it should be able to, it is all in the same device.
> 
> It might be that once the SERDES interrupts saying it has link we need
> to program the MAC with the result of the in-band signalling. in-band
> then seems a bit pointless. Or we are missing some configuration
> somewhere to tell the MAC to use the in-band signalling result from
> the SERDES.

in-band doesn't become pointless if we can't read from the PHY at the
other end of the in-band link (for example, a Microtik copper SFP
module with an AR8033 on, which has no connectivity to the host other
than the serdes lane.)

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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