Data Sheet

Interconnects—Ethernet Controller I210

3.7.4.2.3 Forcing Link-up in 1000BASE-KX Mode

In 1000BASE-KX mode (EXT_CTRL.LINK_MODE = 01b) the I210 should always operates in force link

mode (CTRL.SLU bit is set to 1b). The MAC PCS logic is placed in a link-up state once energy indication

is received, implying that a valid signal is being received by the 1000BASE-KX circuitry. When in the

link-up state PCS logic can lock on incoming characters.

Note: In 1000BASE-KX mode energy detect source is internal and value of CONNSW.ENRGSRC bit

should be 0b. Clause 37 auto-negotiation should be disabled and the value of the

PCS_LCTL.AN_ENABLE bit and PCS_LCTL.AN TIMEOUT EN bit should be 0b.

3.7.4.2.4 1000BASE-KX Hardware Detection of Link Partner

In 1000BASE-KX mode, hardware detects a 1000BASE-KX link partner that sends idle or none idle code

groups continuously. In 1000BASE-KX operation force link-up mode is used.

3.7.4.3 SGMII Link Configuration

When working in SGMII mode, the actual link setting is done by the external PHY and is dependent on

the settings of this PHY. The SGMII auto-negotiation process described in the sections that follow is

only used to establish the MAC/PHY connection.

3.7.4.3.1 SGMII Auto-Negotiation

This auto-negotiation process is not dependent on the SRDS_[n]_SIG_DET signal and the

CONNSW.ENRGSRC bit should be 0b, as this signal indicates optical module signal detection and is not

relevant in SGMII mode.

The outcome of this auto-negotiation process includes the following information:

•Link status

• Speed

•Duplex

This information is used by hardware to configure the MAC, when operating in SGMII mode.

Bits FD and LU of the Device Status (STATUS) register and bits in the PCS_LSTS register provide status

information regarding the negotiated link.

Auto-negotiation can be initiated by the following:

• PCS_LCTL.AN_ENABLE transition from 0b to 1b.

• Receipt of /C/ ordered set during normal operation.

• Receipt of different value of the /C/ ordered set during the negotiation process.

• Transition from loss of synchronization to a synchronized state (if AN_ENABLE is set).

• PCS_LCTL.AN_RESTART transition from 0b to 1b.

Auto-negotiation determines the I210 operation with respect to speed and duplex settings. These

negotiated capabilities override advertised and software controlled device configuration.

When working in SGMII mode, there is no need to set the PCAS_ANADV register, as the MAC

advertisement word is fixed. In SGMII mode the PCS_LCTL.AN TIMEOUT EN bit should be 0b, since

auto-negotiation outcome is required for correct operation. The result of the SGMII level auto-

negotiation can be read from the PCS_LPAB register.