Lower wake up time when phy enter lower mode

Lower wake up time when phy enter lower mode

[Frank Li]

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.

Best regards
Frank Li

Re: Lower wake up time when phy enter lower mode

[Ben Hutchings]

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.

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.

Re: Lower wake up time when phy enter lower mode

[Frank Li]

2012/11/8 Ben Hutchings <bhutchings@solarflare.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?

>
> 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.
>

Re: Lower wake up time when phy enter lower mode

[Ben Hutchings]

On Thu, 2012-11-08 at 10:09 +0800, Frank Li wrote:
> 2012/11/8 Ben Hutchings <bhutchings@solarflare.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.