netdev - Re: [net-next 1/4 (V3)] net: ethtool: add the EEE support

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Date:	Thu, 26 Apr 2012 09:48:28 +0200
From:	Giuseppe CAVALLARO <peppe.cavallaro@...com>
To:	Ben Hutchings <bhutchings@...arflare.com>
Cc:	netdev@...r.kernel.org, rayagond@...avyalabs.com,
	davem@...emloft.net
Subject: Re: [net-next 1/4 (V3)] net: ethtool: add the EEE support

Hello Ben

On 4/19/2012 5:30 PM, Ben Hutchings wrote:
[snip]
>> I'm changing the code for getting/setting the EEE capability and trying
>> to follow your suggestions.
>>
>> The "get" will show the following things; this is a bit different of the
>> points "a" "b" and "c" we had discussed. Maybe, this could also be a
>> more complete (*) .
>> The ethtool (see output below as example) could report the phy
>> (supported/advertised/lp_advertised) and mac eee capabilities separately.
> 
> Sounds reasonable.
> 
>> The "set" will be useful for some eth devices (like the stmmac) that can
>> stop/enable internally the eee capability (at mac level).
> 
> I don't know much about EEE, but shouldn't the driver take care of
> configuring the MAC for this whenever the PHY is set to advertise EEE
> capability?

Yes indeed this can be done at driver level. So could I definitely
remove it from ethtool? What do you suggest?

In case of the stmmac I could add a specific driver option via sys to
enable/disable the eee and set timer.

>> [snip]
>>
>> 	Current message level: 0x0000003f (63)
>> 			       drv probe link timer ifdown ifup
>> 	Link detected: yes
>> 	Energy-Efficient Ethernet:           -------------------------
>> 		MAC supports: yes            |-> related to MAC side  |
>> 		phy supports modes: ...      |-> from MMD 3.20        |
>> 		phy advertising modes: ...   |-> from MMD 7.60        |
>> 		LP advertising modes: ...    |-> from MMD 7.61        |
>> 					     --------------------------
>>                                                     (*)
>> PS. The "..." above means that we can actually dump: 100BASE-TX EEE etc
>> for each advertising modes and also for phy support (reg 3.20).
> 
> Yes, that's the sort of information I would expect to see (but try to be
> consistent with the wording used for AN).:

e.g. SUPPORTED_100baseT_EEE ... ADVERTISED_<...>

> The EEE advertising mask presumably should be changeable similarly to
> the AN advertising mask ('ethtool -s <devname> eeeadv <mask>').  But I
> don't know how the two advertising masks interact.  Is one supposed to
> be a subset of the other?  Currently ethtool automatically changes the
> AN advertising mask in response to a speed/duplex change; should it also
> try to change the EEE advertising mask?

I've just verified the IEEE (Table 45–150a—EEE advertisement register
(Register 7.60) bit definitions) and sorry for my delay in reply but I
was in trouble because looking at the registers for the phy (I am using)
the reg 7.60 was in RO and I couldn't understand how to set the mask.
I confirm that the Adv reg from the std is R/W and the mask as you
suggest could be set according to the speed.
The EEE should work on duplex mode only.

I wonder so if if the final patch I should have no new option for the
ethtool command and EEE info are directly passed from the kernel like
speed and duplex when call get_settings.

Peppe

> 
> Ben.
> 

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