SMSC LAN9420 - Manual (Page 106)

Single-Chip Ethernet Controller with HP Auto-MDIX Support and PCI Interface
Datasheet
Revision 1.22 (09-25-08) 106 SMSC LAN9420/LAN9420i
DATASHEET
4.3.3 Receive Poll Demand Register (RX_POLL_DEMAND)
This register enables the RX DMAC to check for new descriptors.
Offset: 0008h Size: 32 bits
BITS DESCRIPTION TYPE DEFAULT
31:0 Receive Poll Demand (RPD)
When written with any value, the DMAC will check for receive descriptors.
If no descriptors are available, the receive process returns to the suspended
state and bit 7 of the DMAC_STATUS register (receive buffer unavailable -
RU) is not set. A write to this register is only effective if the receive process
is in the suspended state. A Read of this register will timeout and invalid
data will be returned. WO -