netdev - net: phylink: dsa: mv88e6xxx: flaky link detection on switch ports with internal PHYs

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Date:   Tue, 22 Jan 2019 14:16:09 -0500
From:   John David Anglin <dave.anglin@...l.net>
To:     Russell King <linux@....linux.org.uk>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
        Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org
Subject: net: phylink: dsa: mv88e6xxx: flaky link detection on switch ports
 with internal PHYs

I've been hacking on a espressobin board to try to improve ptp support,
etc.  However, I have
a big problem with link detection on the wan, lan0 and lan1 ports.

I have a standard bridge configuration using systemd-networkd. 
Currently, I'm working with linux
v4.20.2.

From power on, none of the wan, lan0, lan1 or br0 achieve link
(LOWER_UP).  networkctl shows
no carrier for these ports.  Disconnecting and reconnecting cables is
not detected and makes no
difference to link state.  I  added a debug printout in
mv88e6352_port_link_state, but the routine
is not called.  As far as I can tell, link state changes are not
detected using PHY interrupts.  And yet,
if the card is rebooted, link detection seems to magically work.

I know that the 88E6341 port registers detect port link (also RJ45 LED)
correctly.

The attached patch fixes link detection at power on.  However, link
state still doesn't update if a cable
is disconnected or moved.

I'm puzzled as to how this is supposed to work.  Thoughts?

Regards,
Dave Anglin

-- 
John David Anglin  dave.anglin@...l.net

View attachment "phylink.c.d" of type "text/plain" (447 bytes)