netdev - Re: Cutting the link on ndo_stop - phy_stop or phy

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Message-ID: <20190604200713.GV19627@lunn.ch>
Date:   Tue, 4 Jun 2019 22:07:13 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     "linux@...linux.org.uk" <linux@...linux.org.uk>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Ioana Ciornei <ioana.ciornei@....com>
Subject: Re: Cutting the link on ndo_stop - phy_stop or phy_disconnect?

On Tue, Jun 04, 2019 at 10:58:41PM +0300, Vladimir Oltean wrote:
> Hi,
> 
> I've been wondering what is the correct approach to cut the Ethernet link
> when the user requests it to be administratively down (aka ip link set dev
> eth0 down).
> Most of the Ethernet drivers simply call phy_stop or the phylink equivalent.
> This leaves an Ethernet link between the PHY and its link partner.
> The Freescale gianfar driver (authored by Andy Fleming who also authored the
> phylib) does a phy_disconnect here. It may seem a bit overkill, but of the
> extra things it does, it calls phy_suspend where most PHY drivers set the
> BMCR_PDOWN bit. Only this achieves the intended purpose of also cutting the
> link partner's link on 'ip link set dev eth0 down'.

Hi Vladimir

Heiner knows the state machine better than i. But when we transition
to PHY_HALTED, as part of phy_stop(), it should do a phy_suspend().

   Andrew