dec21140 network driver

[Emmanuel Raguet]

Jay Kulpinski wrote:
> 
> Is the dec21140 driver in rtems-4.5.0-beta3/c/src/libchip/network/dec21140.c
> the latest version?  This uses busy polling in sendpacket() to wait for
> transmission and memcpy to build a contiguous packet from the mbuf list.
> I thought Eric V. (or was it Emmanuel?) had merged in the changes I made
> to wait on a semaphore and use scatter/gather DMA to send the packet,
> eliminating the copy.  Was there a problem that led to reverting to the
> older version?

Eric and I have performed performance tests and it appears that :
 - For Tx, the memcpy is more efficient than the DMA procedure
 - For Rx, the DMA procedure is more efficient.

You can see the tests results in the file
rtems-4.5.0-beta3/c/src/libchip/network/README.dec21140

Concerning the use of semaphore, I don't remember the changes (and who
was in charge of merging them). Maybe Joel can answer...

Regards 

Emmanuel