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82575EB Gigabit Ethernet Controller — SerDes Link Configuration
Intel
®
82575EB Gigabit Ethernet Controller 324632-003
Software Developer’s Manual and EEPROM Guide Revision: 2.1
248 January 2011
there is a valid signal being received by the optics or the SerDes. The source of the signal
detect is a fixed bit (ENRGSRC) in register CONNSW.
An interrupt bit (RXCFG) has been added to the interrupt registers to flag software that the hardware is
receiving configuration symbols (/C/ codes). Software should unmask (enable) this interrupt when
forcing link. When the link is forced, the link partner can begin to Auto-Negotiate based due to a reset
or enabling of Auto-Negotiation. The reception of /C/ codes causes an interrupt to software and the
proper hardware configuration might be set.
9.3.1.4 Hardware Detection of Non-Auto-Negotiation Partner
Hardware can detect a SerDes partner that sends idle code groups continuously but do not initiate or
answer to an auto-negotiation process. In this case, hardware initiates an auto-negotiation process,
and if it fails after some timeout, a link up is assumed. To enable this functionality the
PCS_LCTL.AN_TIMEOUT_EN bit should be set.
9.3.1.5 SGMII Auto-Negotiation
SGMII protocol includes an auto-negotiation process in order to establish the MAC to PHY connection.
This auto-negotiation process is not dependent on the SRDS0/1_SIG_DET signal, as this signal
indicates the status of the PHY signal detection (usually used in Optical PHY).
The outcome of this auto-negotiation information process is as follows:
• 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 register (STATUS) and bits in the PCS_LSTS register provide status
information regarding the negotiated link.
Auto-Negotiation may be initiated by the following:
• LRST transition from 1b to 0b
• PCS_LCMD.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 synchronized state (if AN_ENABLE is set).
• PCS_LCMD.AN_RESTART transition from 0b to 1b
Resolution of the negotiated link determines 82575 operation with respect to speed and duplex
settings. These negotiated capabilities override advertised and software controlled 82575 configuration.
When operating in SGMII mode, there is no need to set the PCAS_ANADV register, as the MAC
advertisement word is fixed. The result of the SGMII level auto-negotiation can be read from the
PCS_LPAB register.