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

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Message-ID: <9e3c2b6e-b1f8-7e43-2561-30aa84d356c7@prevas.dk>
Date:   Thu, 27 Aug 2020 12:08:31 +0200
From:   Rasmus Villemoes <rasmus.villemoes@...vas.dk>
To:     Network Development <netdev@...r.kernel.org>
Cc:     Lasse Klok Mikkelsen <Lasse.Klok@...vas.se>
Subject: powering off phys on 'ip link set down'

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?

Thanks,
Rasmus