Data Sheet

Ethernet Controller I210 —Interconnects
122
3.7.8.5.4.1 D0a State
A power-managed link speed control lowers link speed (and power) when highest link performance is
not required. When enabled (D0 Low Power Link Up mode), any link negotiation tries to establish a low-
link speed, starting with an initial advertisement defined by software.
The D0LPLU configuration bit enables D0 Low Power Link Up. Before enabling this feature, software
must advertise to one of the following speed combinations: 10 Mb/s only, 10/100 Mb/s only, or 10/100/
1000 Mb/s.
When speed negotiation starts, the PHY tries to negotiate at a speed based on the currently advertised
values. If link establishment fails, the PHY tries to negotiate with different speeds; it enables all speeds
up to the lowest speed supported by the partner. For example, PHY advertises 10 Mb/s only, and the
partner supports 1000 Mb/s only. After the first try fails, the PHY enables 10/100/1000 Mb/s and tries
again. The PHY continues to try and establish a link until it succeeds or until it is instructed otherwise.
In the second step (adjusting to partner speed), the PHY also enables parallel detect, if needed.
Automatic MDI/MDI-X resolution is done during the first auto-negotiation stage.
3.7.8.5.4.2 Non-D0a State
The PHY might negotiate to a low speed while in non-D0a states (Dr, D0u, D3). This applies only when
the link is required by one of the following: Manageability, APM Wake, or PME. Otherwise, the PHY is
disabled during the non-D0 state.
The Low Power on Link-Up (register PHPM.LPLU, is also loaded from Flash) bit enables reduction in link
speed:
• At power-up entry to Dr state, the PHY advertises supports for 10 Mb/s only and goes through the
link up process.
• At any entry to a non-D0a state (Dr, D0u, D3), the PHY advertises support for 10 Mb/s only and
goes through the link up process.
• While in a non-D0 state, if auto-negotiation is required, the PHY advertises support for 10 Mb/s only
and goes through the link up process.
Link negotiation begins with the PHY trying to negotiate at 10 Mb/s speed only regardless of user auto-
negotiation advertisement. If link establishment fails, the PHY tries to negotiate at additional speeds; it
enables all speeds up to the lowest speed supported by the partner. For example, the PHY advertises
10 Mb/s only and the partner supports 1000 Mb/s only. After the first try fails, PHY enables 10/100/
1000 Mb/s and tries again. The PHY continues to try and establish a link until it succeeds or until it is
instructed otherwise. In the second step (adjusting to partner speed), the PHY also enables parallel
detect, if needed. Automatic MDI/MDI-X resolution is done during the first auto-negotiation stage.
3.7.8.5.5 Internal PHY Smart Power-Down (SPD)
SPD is a link-disconnect capability applicable to all power management states. SPD combines a power
saving mechanism with the fact that the link might disappear and resume.
SPD is enabled by PHPM.SPD_EN or by SPD Enable bit in the Flash if the following conditions are met:
1. Auto-negotiation is enabled.
2. PHY detects link loss.
While in SPD, the PHY powers down circuits and clocks that are not required for detection of link
activity. The PHY is still be able to detect link pulses (including parallel detect) and wake-up to engage
in link negotiation. The PHY does not send link pulses (NLP) while in SPD state; however, register
accesses are still possible.