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

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Date:   Wed, 5 Jun 2019 11:01:10 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc:     Vladimir Oltean <olteanv@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "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 6/5/2019 1:45 AM, Russell King - ARM Linux admin wrote:
> On Tue, Jun 04, 2019 at 07:25:46PM -0700, Florian Fainelli wrote:
>> On 6/4/2019 2:36 PM, Russell King - ARM Linux admin wrote:
>>> Normally the PHY receives traffic, and passes it to the MAC which
>>> just ignores the signals it receives from the PHY, so no processing
>>> beyond the PHY receiving the traffic happens.
>>>
>>> Ultimately, whether you want the PHY to stay linked or not linked
>>> is, imho, a policy that should be set by the administrator (consider
>>> where a system needs to become available quickly after boot vs a
>>> system where power saving is important.)  We don't, however, have
>>> a facility to specify that policy though.
>>
>> Maybe that's what we need, something like:
>>
>> ip link set dev eth0 phy [on|off|wake]
>>
>> or whatever we deem appropriate such that people willing to maintain the
>> PHY on can do that.
> 
> How would that work when the PHY isn't bound to the network device until
> the network device is brought up?

There was supposed to be a down somewhere, something like:

ip link set dev eth0 down phy [on|off|wake]

such that we have been guaranteed to be connected to the PHY at some
point. Maybe this is not such a great idea after all, since not all
drivers would be able to support the optional "phy" argument.
-- 
Florian