MPC860-T / FEC transmits each packet 3 times?

MPC860-T / FEC transmits each packet 3 times?

[Wolfgang Denk]

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@denx.de
Imagination is more important than knowledge.      -- Albert Einstein

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: MPC860-T / FEC transmits each packet 3 times?

[Graham Stoney]

On Wed, Nov 22, 2000 at 11:14:41PM +0100, Wolfgang Denk wrote:
> Any ideas what I am missing?

My best guess is to check your buffer descriptor settings.  Are you setting
the L and W bits in your single BD?  I assume you're polling the BD to
determine when the frame has been sent; are there any errors?  In particular,
is the Retry Count field non-zero?  Is your polling code inadvertently writing
to the BD (rather than just reading it) and setting the R bit again?

Regards,
Graham
--
Graham Stoney
Assistant Technology Manager
Canon Information Systems Research Australia
Ph: +61 2 9805 2909  Fax: +61 2 9805 2929

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: MPC860-T / FEC transmits each packet 3 times?

[Tom Armistead]

Hi,

   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@denx.de
> Imagination is more important than knowledge.      -- Albert Einstein
>

--
Tom Armistead

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: MPC860-T / FEC transmits each packet 3 times?

[Wolfgang Denk]

In message <3A229278.C774FB4@phx.mcd.mot.com> Tom Armistead wrote:
>
>    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.

Thank you very much - that was exactly the problem I had.

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
Status quo. Latin for "the mess we're in."

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/