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MPC8260 ethernet BD updates ...



Hello all,

I am working on an ethernet driver on the mpc8260ADS-P board for ECOS 
and got it working with one Tx buffer descriptor. With multiple TxBD's, 
the CP behaves a little different than I expected:

The CP checks the first TxBD and sends it when it is ready. However, it 
won't advance the TBPTR (in FCC parameter RAM) and keeps checking the 
ready bit of the first TxBD. The second, third ... and the last BD ready 
bits are set and nothing happens. When I set to the first BD ready bit 
again, the CP realizes that all BD's are ready and sends them all out. 

In summary : 
 -> CP polls only the first BD 
 -> If it is ready, then the CP sends out all consecutive buffers that 
    are ready ... 

1) Is it supposed to work this way ? If so, I can make the driver work
with minor modifications. But digging through the user's manual, 
(page 28-10, page 28-12 definition of TBPTR), i have the impression that 
the CP is supposed to poll the second TxBD after sending the first one. 

2) If it is not supposed to work this way, what might be wrong ? 

Any ideas and comments appreciated ...

Nejat Tek
Software Engineer
Delphi Communication Systems, Inc.


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