On Oct 16, 2013, at 10:40 AM, David Hawkins wrote: > 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). It would definitely be interesting to see whether the FPGA address space can be accessed using DMA initiated from the PPC side. > 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. :-) Dave
