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Software Developer’s Manual 131
Power Management
Power Management 6
6.1 Introduction to Power Management
The PCI/PCI-X Family of Gigabit Ethernet Controllers support the Advanced Configuration and
Power Interface (ACPI) specification as well as Advanced Power Management (APM). This
section describes how Power Management is implemented in the Ethernet controllers.
Note: The 82541ER does not support ACPI or APM wakeup.
Power Management can be disabled via bits in the Initialization Control Word 2 which is loaded
from the EEPROM during power-up reset. See the EEPROM description in Section 5.6.12 for
further details. Even when disabled, the Power Management register set is still present.
The Ethernet controller supports the following Power Management related features:
• Power states of D0 & D3
hot
with optional D3
cold
support
• Power(D3) < Power(D0)
• Wakeup
6.2 Assumptions
The following assumptions apply to the implementation of Power Management for the Ethernet
controller.
• Any time LAN_PWR_GOOD is asserted all power supplies are stable, RST# is stable, and the
clock is stable.
• Prior to transition from D0 to the D3 state, the operating system ensures that the software
device driver is disabled and all pending bus transactions are complete or cleanly terminated.
• The driver sets up the filters prior to the system transitioning the Ethernet controller to the D3
state.
• The system never deactivates the PCI clock in 66 MHz PCI mode or any PCI-X
1
mode without
asserting RST#.
• No wakeup capability, except APM Wakeup if enabled in the EEPROM, is required after the
system asserts, then de-asserts RST#.
• No wakeup capability, except APM Wakeup if enabled in the EEPROM, is required after the
system puts the Ethernet controller in the D3 state and then returns it to D0.
• If the APMPME bit (bit 3) in the Wakeup Control Register (WUC.APMPME) is set to 1b, it is
permissible to assert PME# even when
PME_En is 0b.
• The deassertion (rising) edge of RST# puts the Ethernet controller in the D0u state.
1. The 82540EP/EM, 82541xx, and 82547GI/EI do not support PCI-X mode.