IDT 89HPES16NT2, User Manual

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Notes
PES16NT2 User Manual 5 - 1 April 15, 2008
®
Chapter 5
Power Management
Introduction
A power management capability structure is located in the configuration space of each PCI-PCI bridge
in the PES16NT2. The structure associated with a PCI-PCI bridge of a downstream port only affects that
port. Entering the D3
hot
state allows the link associated with the bridge to enter the L1 state.
The power management capability structure associated with the root port (i.e., port A) affects the entire
device. When the root port enters a low power state and the PME_TO_Ack messages are received, then
the entire device is placed into a low power state. The PES16NT2 supports the following device power
management states: D0 Uninitialized, D0 Active, D3
hot
, and D3
cold
. Transitioning a port’s power manage-
ment state from D3
hot
to D0
uninitialized
does not result in any logic being reset or re-initialization of register
values.
A power management state transition diagram for the states supported by the PES16NT2 is provided in
Figure 5.1 and described in Table 5.1.
Figure 5.1 PES16NT2 Power Management State Transition Diagram
D0
Uninitialized
D0
Active
D3
hot
Power-On Reset
D3
cold