[PATCH 03/12] fs_enet: Add FEC TX Alignment workaround for MPC5121.

Wolfgang Denk wd at denx.de
Thu May 7 08:12:50 EST 2009


Dear Grant Likely,

In message <fa686aa40905061337w6aa82f5aj787618ba108e528f at mail.gmail.com> you wrote:
>
> > The FEC on 5121 has problems with misaligned tx buffers.
> > The RM says any alignment is ok but empirical results
> > show that packet buffers ending in 0x1E will sometimes
> > hang the FEC. Other bad alignment does not hang but will
> > cause silent TX failures resulting in about a 1% packet
> > loss as tested by ping -f from a remote host.
> >
> > This patch is a work around that copies every tx packet
> > to an aligned skb before sending.
>
> OUCH!

Yes :-(

> > +#else
> > +#define tx_skb_align_workaround(dev, skb) (skb)
> > +#endif
>
> Another use of #ifdef blocks.  What is the multiplatform impact?

Hm... Can you recommend a better way to solve the problem? Suggestions
are welcome.

Best regards,

Wolfgang Denk

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