Subject: Re: [PATCH 2.6.38.4] mii: add support of pause frames in mii_get_an

From: Stephen Hemminger <[email-masked]>
Date: Wed, 27 Apr 2011 21:49:02 -0700

On Thu, 28 Apr 2011 10:49:14 +0700
artpol <[email-masked]> wrote:

> Add support of pause frames advertise in mii_get_an. This provides all drivers 
> that use mii_ethtool_gset to represent their own and Link partner flow control
> abilities in ethtool.
> 
> Signed-off-by: Artem Polyakov <[email-masked]>
> 
> ---
> 
> --- linux-2.6.38.4/drivers/net/mii.c.orig	2011-04-28 08:46:13.000000000 +0700
> +++ linux-2.6.38.4/drivers/net/mii.c	2011-04-25 23:04:20.694981968 +0700
> @@ -49,6 +49,10 @@ static u32 mii_get_an(struct mii_if_info
>  		result |= ADVERTISED_100baseT_Half;
>  	if (advert & ADVERTISE_100FULL)
>  		result |= ADVERTISED_100baseT_Full;
> +	if (advert & ADVERTISE_PAUSE_CAP)
> +		result |= ADVERTISED_Pause;
> +	if (advert & ADVERTISE_PAUSE_ASYM)
> +		result |= ADVERTISED_Asym_Pause;
>  
>  	return result;
>  }

One common driver problem is that auto negotiation of pause
is really a separate operation from negotiation of speed.
It should be possible to force no flow-control but still negotiate
speed and vice-versa.  The ethtool api breaks this into two operations
but many drivers munge them together.