Power Management; Introduction - Renesas IDT 89HPES48H12G2 User Manual

Notes
PES48H12G2 User Manual
®

Introduction

Located in configuration space of each Function in the PES48H12G2 (i.e., PCI-to-PCI Bridge Function)
is a power management capability structure. PES48H12G2 Functions support the following device power
management states:
– D0 (D0 and D0
uninitialized
– D3
Hot
– D3 .
Cold
A power management state transition diagram for the states supported by the PES48H12G2 is provided
in Figure 11.1 and described in Table 11.1. Transitioning a Function's power management state from D3
to D0 does not result in any logic being reset or re-initialization of register values. Thus, the default
uninitialized
value of the No Soft Reset (NOSOFTRST) bit in the Function's PCI Power Management Control and Status
(PMCSR) register corresponds to the functional context being maintained in the D3
The power management capability structure associated with each Function affects the power state of
that Function only. In addition, the power management capability structure associated with an upstream
port's PCI-to-PCI Bridge Function affects the switch partition with which the port is associated. When the
upstream PCI-to-PCI bridge Function enters the D3
(i.e., PME_TO_Ack messages are received), then the switch partition associated with the Function is
placed into a low power state.
– The entire PES48H12G2 device enters a low power state when all active partitions (i.e., ones
whose state is not disabled) are in a low power state.
The link's power state is derived from the power state of the Function(s) in the port. When a Function
enters the D0 state (i.e., D0
uninitialized
When a Function enters the D3
– A port configured in 'Upstream Switch Port' mode initiates entry into L1 when all the Functions in
the port enter the D3
– A port configured in 'Downstream Switch Port' mode always accepts entry into L1 when requested
1
by the link partner.
1.
This applies when entry into L1 is a result of the link partner being placed in D3hot. This does not apply for entry
into L1-ASPM, where the L1 entry request may be rejected by the downstream port. Refer to section Active State
Power Management on page 7-11 for further details on L1 ASPM.

Power Management

)
active
state and the PME Turn Off protocol is completed
Hot
or D0 ), the Function transitions the port's link to the L0 state.
active
state, the Function transitions the port's link to the L1 state.
Hot
state.
Hot
11 - 1
Chapter 11
hot
state.
hot
April 5, 2013