MPC860-T / FEC transmits each packet 3 times?

Tom Armistead tarmiste at
Tue Nov 28 03:57:28 EST 2000


   I experienced the same behaviour when I had initialized the FEC to
use only 1 transmit BD (it was a simple application and I only needed 1
transmit buffer).  I modified the code to use 2 transmit BD's and the
problem went away.  If you are using only a single transmit BD, try
increasing it to 2.

Tom Armistead

Wolfgang Denk wrote:
> Hi,
> I'm struggeling with an Ethernet driver on the FEC of a MPC860-T.  To
> the   best   of  my  knowledge,  I'm  doing  everything  strictly  as
> documented, and as other drivers do it. However,  even  when  I  just
> want to send a single packet (no interrrupts, everything as simple as
> possible),  the package is sent 3 times to the wire; sometimes even 4
> times. I don't see any indication of this in  the  software,  just  3
> packets  on  the wire, usually 5...9 us apart (on a 100 Mbps net; the
> packets come after 300...320 us on a 10 Mbps net).
> Playing with half or full duplex mode didn't change anything. In case
> it matters: it's a LXT972LC PHY. Ummm.. and yes, I can  be  sure  the
> hardware is working OK. It does so in another OS...
> Any ideas what I am missing?
> Wolfgang Denk
> --
> Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
> Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at
> Imagination is more important than knowledge.      -- Albert Einstein

Tom Armistead

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