SMSC LAN9311i - Manual (Page 182)

Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface
Datasheet
Revision 1.4 (08-19-08) 182 SMSC LAN9311/LAN9311i
DATASHEET
14:13 RESERVED RO -
12:8 RX Data Offset (RXDOFF)
This field controls the offset value, in bytes, that is added to the beginning
of an RX data packet. The start of the valid data will be shifted by the
number of bytes specified in this field. An offset of 0-31 bytes is a valid
number of offset bytes.
Note: The two LSBs of this field (D[9:8]) must not be modified while the
RX is running. The receiver must be halted, and all data purged
before these two bits can be modified. The upper three bits
(DWORD offset) may be modified while the receiver is running.
Modifications to the upper bits will take affect on the next DWORD
read.
R/W 00000b
7:0 RESERVED RO -
BITS DESCRIPTION TYPE DEFAULT