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4.45 Power Management Control/Status Bridge Support Extensions Register
This register supports PCI bridge-specific functionality. It is required for all PCI-to-PCI bridges. See Table 4−21 for
a complete description of the register contents.
Bit 7 6 5 4 3 2 1 0
Name Power management control/status bridge support extensions
Type R R R R R R R R
Default 1 1 0 0 0 0 0 0
Register: Power management control/status bridge support extensions
Offset: A6h (Functions 0, 1)
Type: Read-only
Default: C0h
Table 4−21. Power Management Control/Status Bridge Support Extensions Register Description
BIT SIGNAL TYPE FUNCTION
7 BPCC_EN R
Bus power/clock control enable. This bit returns 1 when read. This bit is encoded as:
0 = Bus power/clock control is disabled.
1 = Bus power/clock control is enabled (default).
A 0 indicates that the bus power/clock control policies defined in the PCI Bus Power Management Interface
Specification are disabled. When the bus power/clock control enable mechanism is disabled, the power
state field (bits 1−0) of the power management control/status register (PCI offset A4h, see Section 4.44)
cannot be used by the system software to control the power or the clock of the secondary bus. A 1 indicates
that the bus power/clock control mechanism is enabled.
6 B2_B3 R
B2/B3 support for D3
hot
. The state of this bit determines the action that is to occur as a direct result of
programming the function to D3
hot
. This bit is only meaningful if bit 7 (BPCC_EN) is a 1. This bit is encoded
as:
0 = When the bridge is programmed to D3
hot
, its secondary bus has its power removed (B3).
1 = When the bridge function is programmed to D3
hot
, its secondary bus PCI clock is stopped (B2)
(default).
5−0 RSVD R Reserved. These bits return 0s when read.
4.46 Power-Management Data Register
The power-management data register returns 0s when read, because the CardBus functions do not report dynamic
data.
Bit 7 6 5 4 3 2 1 0
Name Power-management data
Type R R R R R R R R
Default 0 0 0 0 0 0 0 0
Register: Power-management data
Offset: A7h (functions 0, 1)
Type: Read-only
Default: 00h