netdev - Re: Lower wake up time when phy enter lower mode

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Message-ID: <1352473639.3159.3.camel@bwh-desktop.uk.solarflarecom.com>
Date:	Fri, 9 Nov 2012 15:07:19 +0000
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Frank Li <lznuaa@...il.com>
CC:	Richard Cochran <richardcochran@...il.com>,
	<netdev@...r.kernel.org>
Subject: Re: Lower wake up time when phy enter lower mode

On Thu, 2012-11-08 at 10:09 +0800, Frank Li wrote:
> 2012/11/8 Ben Hutchings <bhutchings@...arflare.com>:
> > On Wed, 2012-11-07 at 10:52 +0800, Frank Li wrote:
> >> Richard:
> >>
> >>           Recently, I found out the path delay will increase about
> >> 20us suddenly in something when connect two iMX6 board and Ethernet
> >> work on 1G mode.
> >>           The reason is that the PHY enter lower mode automatically
> >> when no package send and receive. It takes some time to recover and
> >> send out package by PHY but MAC think package have sent and sample
> >> time stamper.
> >>           Do you meet such case?  I can workaround it by two method
> >>                1. disable phy lower power feature.
> >>                2. add some dummy package before SYNC package.
> >
> > If this low power mode is related to EEE (Energy Efficient Ethernet)
> > then there are ethtool operations defined for configuring it, and you
> > could implement those.
> 
> Yes, it is phy specific, called smart EEE, which compatible with IEEE 802.3az
> and can be used in legacy MAC without EEE.
> 
> Do you have example about ethtool operations?

Look at the comments on struct ethtool_eee in <uapi/linux/ethtool.h>,
and the existing implementations:

drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c
drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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