netdev - Re: [PATCH] gianfar: Fix half-duplex operation for non-MII/RMII interfaces

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Date:	Thu, 25 Jun 2009 01:50:41 +0400
From:	Anton Vorontsov <cbouatmailru@...il.com>
To:	Andy Fleming <afleming@...escale.com>
Cc:	David Miller <davem@...emloft.net>,
	Kumar Gala <galak@...nel.crashing.org>,
	Li Yang <leoli@...escale.com>, linuxppc-dev@...abs.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH] gianfar: Fix half-duplex operation for non-MII/RMII
	interfaces

On Thu, Jun 25, 2009 at 01:39:45AM +0400, Anton Vorontsov wrote:
> On Wed, Jun 24, 2009 at 04:25:06PM -0500, Andy Fleming wrote:
> [...]
> >>> My concern is that you will be detecting the GMII interface, and
> >>> disallowing half-duplex, despite the fact that the interface is  
> >>> actually
> >>> running at 10 or 100 Mbit.
> >>
> >> Very interesting, though I'm not sure I'm completely following. :-)
> >>
> >> Are you saying that I should do this instead:
> >>
> >> 	if (!phydev->duplex &&
> >> 			(phyi == PHY_INTERFACE_MODE_MII ||
> >> 			 phyi == PHY_INTERFACE_MODE_RMII ||
> >> 			 (phyi == PHY_INTERFACE_MODE_GMII &&
> >> 			  phydev->speed < 1000)))
> >> 		tempval &= ~MACCFG2_FULL_DUPLEX;
> >> 	else
> >> 		tempval |= MACCFG2_FULL_DUPLEX;
> >>
> >> i.e. we detected GMII interface initially, but it downgraded
> >> to MII since speed is < 1000, thus we can set half-duplex in MAC?
> >
> > Yeah, I think that works out more correctly.
> 
> Cool, thanks.
> 
> Do you happen to know how gianfar iface auto-detection works in HW?
> I mean, if we connect 100 Mbs link to the GMII PHY, then
> gfar_get_interface() would return MII, correct?

Stupid me. HW has nothing to do with this. GMII, just as you said,
is just a marker, comes from FSL_GIANFAR_DEV_HAS_GIGABIT flag.

-- 
Anton Vorontsov
email: cbouatmailru@...il.com
irc://irc.freenode.net/bd2
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