Data Sheet

Interconnects—Ethernet Controller I210
111
3.7.7.3 EEE Auto-Negotiation
Auto-negotiation provides the capability to negotiate EEE capabilities with the link partner using the
next page mechanism defined in IEEE802.3 Annex 28C. IEEE802.3 auto-negotiation is performed at
power up, on command from software, upon detection of a PHY error or following link re-connection.
During the link establishment process, both link partners indicate their EEE capabilities via the
IEEE802.3 auto-negotiation process. If EEE is supported by both link partners for the negotiated PHY
type then the EEE function can be used independently in either direction.
When operating in internal PHY mode (CTRL_EXT.LINK_MODE = 00b), the I210 supports EEE auto-
negotiation. EEE capabilities advertised during auto-negotiation can be modified via the EEE
advertisement field in the internal PHY (refer to Section 8.27.3.15) or via the EEER.EEE_1G_AN and
EEER.EEE_100M_AN bits.
3.7.7.4 EEE Link Level (LLDP) Capabilities Discovery
When operating in internal PHY mode (CTRL_EXT.LINK_MODE = 00b), the I210 supports LLDP
negotiation via software, using the EEE IEEE802.1AB Link Layer Discovery Protocol (LLDP) Type,
Length, Value (TLV) fields defined in IEEE802.3az clause 78 and clause 79. LLDP negotiation enables
negotiation of increased system wake time (Transmit T
w
and Receive T
w
) to enable improving system
energy efficiency.
After software negotiates a new system wake time via EEE LLDP negotiation, software should update
the:
1. EEER.Tw_system field with the negotiated Transmit T
w
time value, to increase the duration where
idle symbols are transmitted following move out of EEE Tx LPI state before actual data can be
transmitted.
— Value placed in EEER.Tw_system field does not affect transmission of flow control packets.
Depending on the technology (100BASE-TX or 1000BASE-T) flow control packet transmission is
delayed following move out of EEE TX LPI state only by the minimum Tw_sys_tx time as defined
in IEEE802.3az clause 78.5.
2. The LTRMAXV register with a value:
LTRMINV =< LTRMAXV <= LTRMINV + negotiated Receive T
w
Time.
3. Set LTRC.EEEMS_EN bit to 1b (if bit was cleared), so that on detection of EEE RX LPI on the
network an updated LTR message with the value programmed in the LTRMAXV register is sent on
the PCIe interface.
4. Set EEER.TX_LPI_EN bit to 1b (if bit was cleared), to enable entry into EEE LPI on Tx path.
Set EEER.RX_LPI_EN bit to 1b (if bit was cleared), to enable detection of link partner entering EEE LPI
state on Rx path. Once the LTRC.EEEMS_EN bit is set and a port detects link partner entry into the EEE
LPI state on the internal xxMII RX interface, the port increases its reported latency tolerance to the
value programed in the LTRMAXV register. On detection of the Rx EEE LPI state, an updated LTR
message is sent on the PCIe interface.
When wake symbols are detected on the Ethernet link, due to a link partner moving out of EEE Rx LPI
state, the port reports a reduced latency tolerance that equals the value placed in the LTRMINV register
and the I210 sends on the PCIe interface a new LTR message with a reduced latency tolerance value of
LTRMINV.