Hi Dave,
Boot the board, stop in U-Boot, write to the DMA registers
directly, and probe the bus to see what the maximum rate possible
is ... then you can decide whether to write a device driver to use
the DMA controller under Linux.
Oh, yeah, trying to use the DMA controllers on the PPC side would be
very interesting! I was referring to the CASPER implementation of
the FPGA side of the EPB bus not supporting being a DMA bus master
(I'm not even sure that the EPB bus supports external DMA bus
masters).
The 440EP and the Freescale processors do not support external
DMA masters ... in fact, I'm not sure that I have seen any
recent processor that supports this feature (I've looked at
many ARM-based processor data sheets). Although I think its
a common feature on DSP processors ...
If Ross has never had to do this before, he might not have
appreciated where to look/where to start.
If Ross has never had to do this before, he's probably better off
using the pre-canned "Ethernet directly from the FPGA" solution
rather than (re-)writing a Linux device driver to use DMA. :-)
Sure, I was just adding to his list of options :)
Cheers,
Dave
