> I checked port configuration and clock routing registers in > cpm2_io/fcc_enet.c again and again, but all I get in and out is ones. > > The packet sizes I receive look reasonable, but the buffers are > filled only with 0xff. The same goes for sending, the contents > of the buffers are OK (dhcp discover...), but when capturing > the output on the other side with ethereal, the packet is again > all 0xff. > > We just discovered that apparently preamble, frame delimiter and FCS go > out over the MII (at least TxD[0:3] change state), so I don't suspect a > hardware bug. >
I would guess the problem is at the DMA level, that the FCC is reading/writing ffs to/from memory for some reason. The preamble and FCS come from the FCC itself, not memory, so that's why you see them. I'd guess some kind of mismatch with the kind of cycles generated by the FCC DMA and the memory controllers. Mark Chambers
