RE: [E1000-devel] igb: question regarding auto-negotiation

[Pieper, Jeffrey E]

-Original Message-
From: Dominic Curran [mailto:dominic.cur...@citrix.com] 
Sent: Thursday, August 04, 2016 4:02 PM
To: Alexander Duyck <alexander.du...@gmail.com>; 
e1000-de...@lists.sourceforge.net
Cc: Netdev <netdev@vger.kernel.org>
Subject: Re: [E1000-devel] igb: question regarding auto-negotiation



On 07/29/2016 09:35 PM, Alexander Duyck wrote:
> On Fri, Jul 29, 2016 at 4:37 PM, Dominic Curran
> <dominic.cur...@citrix.com> wrote:
>> Hi
>>
>> This question refers to igb codebase.
>> I have a question regarding the setting of hw->mac.autoneg.
>>
>> Is it correct to say for igb driver:
>> "if speed=1000 and duplex=FULL and media_type=COPPER  then  only
>> auto-negotiate enable is supported"
>>
>> i.e.
>> with these settings (speed/duplex/media_type) then auto-negotiate can
>> _not_ be disabled.  Correct ?
>>
>> I say this for two reasons:
>> 1) The code in igb_set_spd_dplx() seems to indicate it:
>>
>> case SPEED_1000 + DUPLEX_FULL:
>>  mac->autoneg = 1;
>>  adapter->hw.phy.autoneg_advertised = ADVERTISE_1000_FULL;
>>  break;
>>
>> 2) Instrumenting the driver, I always see the autoneg code in
>> e1000_check_for_copper_link_generic()  get called after an igb_reset().
>>
>>
>> Have i understood correctly ?
>>
>> thanks in advance
>> dom
> If you are using copper then you are likely referring to 1000Base-T
> correct?  If so then autonegotation is a requirement.
>
> Here is the wikipedia URL that refers to this:
> https://en.wikipedia.org/wiki/Gigabit_Ethernet#1000BASE-T
>
> Hope this helps to clear it up.
>
> Thanks.
>
> - Alex

Thanks for reply.  I read the wiki link and a bunch of other links besides.

So I have a follow-up question:

You're right I am using copper and 1000Base-T, and as you say auto-neg 
is then requirement.

So why is it possible with the igb driver to set auto-neg to OFF ?

e.g.
# ethtool -a eth6
Pause parameters for eth6:
Autonegotiate:  on
RX: on
TX: on

Now turn it OFF:

# ethtool -A eth6 autoneg off

# ethtool -a eth6
Pause parameters for eth6:
Autonegotiate:  off
RX: on
TX: on

But added debug to the driver I _know_ that it is still 
auto-negotiating, and printing current settings indicates 
'Auto-negotiatiate' is on...

# ethtool  eth6
Settings for eth6:
 Supported ports: [ TP ]
 Supported link modes:   10baseT/Half 10baseT/Full
 100baseT/Half 100baseT/Full
 1000baseT/Full
 Supported pause frame use: No
 Supports auto-negotiation: Yes
 Advertised link modes:  10baseT/Half 10baseT/Full
 100baseT/Half 100baseT/Full
 1000baseT/Full
 Advertised pause frame use: No
 Advertised auto-negotiation: Yes
 Speed: 1000Mb/s
 Duplex: Full
 Port: Twisted Pair
 PHYAD: 1
 Transceiver: internal
 Auto-negotiation: on <<<<
 MDI-X: on
 Supports Wake-on: pumbg
 Wake-on: d
 Current message level: 0x0007 (7)
drv probe link
 Link detected: yes

So I dont understand the difference between these two values ??
Can anyone help please ?

Thanks
dom

Dom,

ethtool -A is used to set flow-control parameters, not speed/duplex/autoneg. 
Speed/duplex parameters are set with ethtool -s. man ethtool should help 
explain the difference.

I hope this helps,
Jeff
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Re: igb: question regarding auto-negotiation

[Dominic Curran]

On 07/29/2016 09:35 PM, Alexander Duyck wrote:

On Fri, Jul 29, 2016 at 4:37 PM, Dominic Curran
 wrote:

Hi

This question refers to igb codebase.
I have a question regarding the setting of hw->mac.autoneg.

Is it correct to say for igb driver:
"if speed=1000 and duplex=FULL and media_type=COPPER  then  only
auto-negotiate enable is supported"

i.e.
with these settings (speed/duplex/media_type) then auto-negotiate can
_not_ be disabled.  Correct ?

I say this for two reasons:
1) The code in igb_set_spd_dplx() seems to indicate it:

case SPEED_1000 + DUPLEX_FULL:
 mac->autoneg = 1;
 adapter->hw.phy.autoneg_advertised = ADVERTISE_1000_FULL;
 break;

2) Instrumenting the driver, I always see the autoneg code in
e1000_check_for_copper_link_generic()  get called after an igb_reset().


Have i understood correctly ?

thanks in advance
dom

If you are using copper then you are likely referring to 1000Base-T
correct?  If so then autonegotation is a requirement.

Here is the wikipedia URL that refers to this:
https://en.wikipedia.org/wiki/Gigabit_Ethernet#1000BASE-T

Hope this helps to clear it up.

Thanks.

- Alex


Thanks for reply.  I read the wiki link and a bunch of other links besides.

So I have a follow-up question:

You're right I am using copper and 1000Base-T, and as you say auto-neg 
is then requirement.


So why is it possible with the igb driver to set auto-neg to OFF ?

e.g.
# ethtool -a eth6
Pause parameters for eth6:
Autonegotiate:  on
RX: on
TX: on

Now turn it OFF:

# ethtool -A eth6 autoneg off

# ethtool -a eth6
Pause parameters for eth6:
Autonegotiate:  off
RX: on
TX: on

But added debug to the driver I _know_ that it is still 
auto-negotiating, and printing current settings indicates 
'Auto-negotiatiate' is on...


# ethtool  eth6
Settings for eth6:
Supported ports: [ TP ]
Supported link modes:   10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes:  10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: No
Advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on 
MDI-X: on
Supports Wake-on: pumbg
Wake-on: d
Current message level: 0x0007 (7)
   drv probe link
Link detected: yes

So I dont understand the difference between these two values ??
Can anyone help please ?

Thanks
dom

Re: igb: question regarding auto-negotiation

[Alexander Duyck]

On Fri, Jul 29, 2016 at 4:37 PM, Dominic Curran
 wrote:
> Hi
>
> This question refers to igb codebase.
> I have a question regarding the setting of hw->mac.autoneg.
>
> Is it correct to say for igb driver:
>"if speed=1000 and duplex=FULL and media_type=COPPER  then  only
> auto-negotiate enable is supported"
>
> i.e.
>with these settings (speed/duplex/media_type) then auto-negotiate can
> _not_ be disabled.  Correct ?
>
> I say this for two reasons:
> 1) The code in igb_set_spd_dplx() seems to indicate it:
>
>case SPEED_1000 + DUPLEX_FULL:
> mac->autoneg = 1;
> adapter->hw.phy.autoneg_advertised = ADVERTISE_1000_FULL;
> break;
>
> 2) Instrumenting the driver, I always see the autoneg code in
> e1000_check_for_copper_link_generic()  get called after an igb_reset().
>
>
> Have i understood correctly ?
>
> thanks in advance
> dom

If you are using copper then you are likely referring to 1000Base-T
correct?  If so then autonegotation is a requirement.

Here is the wikipedia URL that refers to this:
https://en.wikipedia.org/wiki/Gigabit_Ethernet#1000BASE-T

Hope this helps to clear it up.

Thanks.

- Alex

igb: question regarding auto-negotiation

[Dominic Curran]

Hi

This question refers to igb codebase.
I have a question regarding the setting of hw->mac.autoneg.

Is it correct to say for igb driver:
   "if speed=1000 and duplex=FULL and media_type=COPPER  then  only 
auto-negotiate enable is supported"


i.e.
   with these settings (speed/duplex/media_type) then auto-negotiate 
can _not_ be disabled.  Correct ?


I say this for two reasons:
1) The code in igb_set_spd_dplx() seems to indicate it:

   case SPEED_1000 + DUPLEX_FULL:
mac->autoneg = 1;
adapter->hw.phy.autoneg_advertised = ADVERTISE_1000_FULL;
break;

2) Instrumenting the driver, I always see the autoneg code in 
e1000_check_for_copper_link_generic()  get called after an igb_reset().



Have i understood correctly ?

thanks in advance
dom