Thanks Russell, On 09/28/2016 10:25 AM, Russell King - ARM Linux wrote: > On Wed, Sep 28, 2016 at 10:14:52AM -0700, Eric Nelson wrote: >> Thanks David, >> >> On 09/28/2016 09:42 AM, David Laight wrote: >>> From reading this it seems that the effect of FEC_RACC_SHIFT16 is to >>> add two bytes of 'junk' to the start of every receive frame. >> >> That's right. Two bytes of junk between the MAC header and the >> IP header. > > That's wrong. FEC_RACC_SHIFT16 adds two bytes to the _beginning_ of > the packet, not in the middle of the packet: > > 7 RX FIFO Shift-16 > SHIFT16 > When this field is set, the actual frame data starts at bit 16 > of the first word read from the RX FIFO aligning the Ethernet > payload on a 32-bit boundary. > > NOTE: This function only affects the FIFO storage and has no > influence on the statistics, which use the actual length > of the frame received. > > 0 Disabled. > 1 Instructs the MAC to write two additional bytes in front > of each frame received into the RX FIFO. > > *in front* of the frame - that's before the Ethernet header. Not between > the ethernet and IP headers. >
I obviously mis-read this, and haven't dumped any packets to straighten myself out.
