netdev - Re: mv88e6240 configuration broken for B850v3

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Message-ID: <Ya91eO25R/yehy+k@shell.armlinux.org.uk>
Date:   Tue, 7 Dec 2021 14:53:44 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Martyn Welch <martyn.welch@...labora.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        netdev@...r.kernel.org, kernel@...labora.com
Subject: Re: mv88e6240 configuration broken for B850v3

On Tue, Dec 07, 2021 at 04:37:05PM +0200, Vladimir Oltean wrote:
> Although it isn't strictly true that "[ if ] there is a non-software
> method to handle the status updates, then we don't do any forcing in
> the mac_link_*() methods", because technically we still do in
> mac_link_down, due to the " || mode == MLO_AN_FIXED" condition plus the
> way in which we are called, it's just that we undo it later.

Fixed links are a "software method" as Andrew has already pointed
out - there is a software hook that can be used to retrieve the
link status, potentially also updating the other link parameters
as well.

Fixed links have never been "these are the only parameters you will
ever get and the link will always be forced up". That is not new.
Have a look at drivers/net/phy/fixed_phy.c and its link_update()
method, which can change any parameter of the fixed-link it desires.
There is also fixed_phy_change_carrier() which allows one to force
the link state of a fixed-link.

-- 
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