netdev - Re: [PATCH net-next] net: mvpp2: cycle comphy to power it down

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Date:   Thu, 19 Dec 2019 17:27:48 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     rmk+kernel@...linux.org.uk
Cc:     antoine.tenart@...tlin.com, maxime.chevallier@...tlin.com,
        w@....eu, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: mvpp2: cycle comphy to power it down

From: Russell King <rmk+kernel@...linux.org.uk>
Date: Tue, 17 Dec 2019 15:47:36 +0000

> Presently, at boot time, the comphys are enabled. For firmware
> compatibility reasons, the comphy driver does not power down the
> comphys at boot. Consequently, the ethernet comphys are left active
> until the network interfaces are brought through an up/down cycle.
> 
> If the port is never used, the port wastes power needlessly. Arrange
> for the ethernet comphys to be cycled by the mvpp2 driver as if the
> interface went through an up/down cycle during driver probe, thereby
> powering them down.
> 
> This saves:
>   270mW per 10G SFP+ port on the Macchiatobin Single Shot (eth0/eth1)
>   370mW per 10G PHY port on the Macchiatobin Double Shot (eth0/eth1)
>   160mW on the SFP port on either Macchiatobin flavour (eth3)
> 
> Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>

Applied, thanks.