netdev - Re: powering off phys on 'ip link set down'

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Message-ID: <adcbe6fc-6adc-4138-a5d1-77e811f4c0eb@gmail.com>
Date:   Thu, 27 Aug 2020 13:14:13 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        Network Development <netdev@...r.kernel.org>
Cc:     Lasse Klok Mikkelsen <Lasse.Klok@...vas.se>
Subject: Re: powering off phys on 'ip link set down'

On 27.08.2020 13:00, Rasmus Villemoes wrote:
> On 27/08/2020 12.29, Heiner Kallweit wrote:
>> On 27.08.2020 12:08, Rasmus Villemoes wrote:
>>> Hi,
>>>
>>> We have a requirement that when an interface is taken down
>>> administratively, the phy should be powered off. That also works when
>>> the interface has link when the 'ip link set down ...' is run. But if
>>> there's no cable plugged in, the phy stays powered on (as can be seen
>>> both using phytool, and from the fact that a peer gets carrier once a
>>> cable is later plugged in).
>>>
>>> Is this expected behaviour? Driver/device dependent? Can we do anything
>>> to force the phy off?
>>>
>> This may be MAC/PHY-driver dependent. Which driver(s) do we talk about?
> 
> It's a Marvell 88e6250 switch (drivers/net/dsa/mv88e6xxx/).
> 
>> Also it may depend on whether Runtime PM is active for a PCI network
>> device. In addition WoL should be disabled.
> 
> The datasheet does mention WoL, but it's either not hooked up in the
> driver or at least default disabled, ethtool says
> 
>      Supports Wake-on: d
>      Wake-on: d
> 
> Thanks,
> Rasmus
> 

Maybe your question refers to something that was changed in 5.4 with
the following commit:
95fb8bb3181b ("net: phy: force phy suspend when calling phy_stop")