[PATCH] net: EMAC: Fix problem with mtu > 4080 on non TAH equipped 4xx PPC's

[Eugene Surovegin]

On Tue, Jan 15, 2008 at 08:46:01PM +0100, Stefan Roese wrote:
> On Tuesday 15 January 2008, Eugene Surovegin wrote:
> > On Tue, Jan 15, 2008 at 01:40:09PM +0100, Stefan Roese wrote:
> > > Currently, all non TAH equipped 4xx PPC's call emac_start_xmit() upon
> > > xmit. This routine doesn't check if the frame length exceeds the max.
> > > MAL buffer size.
> > >
> > > This patch now changes the driver to call emac_start_xmit_sg() on all
> > > platforms and not only the TAH equipped ones (440GX). This enables an
> > > MTU of 9000 instead 4080.
> > >
> > > Tested on Kilauea (405EX) with gbit link -> jumbo frames enabled.
> > >
> > > Signed-off-by: Stefan Roese <sr at denx.de>
> > > ---
> > > Eugene & Ben, do you see any problems with this patch? If not, then I'll
> > > send another version for the newemac driver too.
> >
> > Hmm, so why not make GigE support a condition to hook SG version of
> > xmit then? I don't like when you change behaviour for chips where it
> > perefectly legal not to do this check because you cannot change MTU
> > anyways.
> 
> OK. But how do we detect GigE support? Seems like GigE enabled devices have 
> CONFIG_IBM_EMAC4 defined. If nobody objects I'll fix up another version 
> tomorrow.

Look couple of lines down where I set MTU changing hook. If you cannot 
change MTU you cannot get big frames.

-- 
Eugene