Data Sheet

Ethernet Controller I210 — Programming Interface
548
8.25.12 Energy Efficient Ethernet (EEE) Register - EEER (0x0E30; R/W)
Field Bit(s) Initial Value Description
Tw_system 15:0 0x0
Time expressed in microseconds that no data is transmitted following a move
from the EEE TX LPI link state to a link active state. This field holds the transmit
Tw_sys_tx value negotiated during EEE LLDP negotiation.
Notes:
1. If this value is lower than the minimum Tw_sys_tx value defined in
IEEE802.3az clause 78.5 (30 s for 100BASE-TX and 16.5 s for 1000BASE-
T) then the interval where no data is transmitted following a move out of
the EEE TX LPI state defaults to a minimum Tw_sys_tx .
2. Following a link disconnect or auto-negotiation the value of this field returns
to its default value until software re-negotiates a new tw_sys_tx value via
EEE LLDP.
Note: When transmitting flow control frames, the I210 waits the minimum
time defined in the IEEE802.3az standard before transmitting a flow
control packet. The I210 does not wait the Tw_system time following an
exit of LPI before transmitting a flow control frame.
TX_LPI_EN 16 0b
1
Enable Entry into EEE LPI on Tx Path.
0b = Disable entry into EEE LPI on Tx path.
1b = Enable entry into EEE LPI on Tx path.
Refer to Section 3.7.7.1 for additional information on EEE Tx LPI entry.
Notes:
1. Even when TX_LPI_EN is set to 1b, the I210 will not enable entry into the
Tx LPI state for at least 1 second following the change of link_status to OK
as defined in IEEE802.3az clause 78.1.2.1.
2. Even if the TX_LPI_EN bit is set, the I210 initiates entry into the Tx EEE LPI
link state only if EEE support at the link speed was negotiated during auto-
negotiation.
RX_LPI_EN 17 1b
Enable Entry into EEE LPI on Rx Path
0b = Disable entry into EEE LPI on Rx path.
1b = Enable entry into EEE LPI on Rx path.
Notes:
1. Even if the RX_LPI_EN bit is set, the I210 recognizes entry into Rx EEE LPI
link state only if EEE support at the link speed was negotiated during auto-
negotiation.
2. When set and link moves into Rx LPI, a LTR message with the value defined
in the LTRMAXV register is sent on the PCIe, if LTRC.EEEMS_EN is set.
LPI_FC 18 1b
Enable EEE Tx LPI Entry on Flow Control.
Enable EEE Tx LPI state entry when the link partner sent a PAUSE flow control
frame, even if the internal transmit buffer is not empty, transmit descriptors are
available or management traffic is pending.
Notes:
1. The I210 enters the Tx LPI state when no data is transmitted and not in
mid-packet.
2. Entry into Tx LPI on flow control is enabled only if either EEER.TX_LPI_EN is
set to 1b or EEER.Force_TLPI is set to 1b.
3. Receiving XON frame causes a move out of LPI if a transmit is pending.
Force_TLPI 19 0b
Force Tx LPI.
When set, the PHY is forced into the EEE Tx LPI state if there is no Tx
management traffic.
Notes:
1. The I210 enters the Tx LPI state when no data is transmitted and not in
mid-packet.
2. When set, the I210 enters Tx LPI even if EEER.TX_LPI_EN is set to 0b.
Reserved 27:20 0x0
Reserved.
Write 0x0, ignore on read.