Avago Technologies LSI53C896 - Manual (Page 87)

Power Management 2-59
Version 3.3 Copyright © 1998–2003 by LSI Logic Corporation. All rights reserved.
LSI53C896 power states shown in Table 2.9 are independently controlled
through two power state bits that are located in the PCI Configuration
Space
Power Management Control/Status (PMCSR) register 0x44–0x45 .
Although the PCI Bus Power Management Interface Specification does
not allow power state transitions D2 to D1, D3 to D2, or D3 to D1, the
LSI53C896 hardware places no restriction on transitions between
power states.
As the device transitions from one power level to a lower one, the
attributes that occur from the higher power state level are carried over
into the lower power state level. For example, D1 disables the SCSI CLK.
Therefore, D2 includes this attribute as well as the attributes defined in
the Power State D2 section. The PCI Function Power States (D0, D1, D2,
and D3) are described in conjunction with each SCSI function. Power
state actions are separate for each function.
2.5.1 Power State D0
Power state D0 is the maximum power state and is the power-up default
state for each function. The LSI53C896 is fully functional in this state.
2.5.2 Power State D1
Power state D1 is a lower power state than D0. A function in this state
places the LSI53C896 core in the snooze mode and disables the SCSI
CLK. In the snooze mode, a SCSI reset does not generate an IRQ/ signal.
Table 2.9 Power States
Configuration Register
0x44 Bits [1:0] Power State Function
00 D0 Maximum Power
01 D1 Disables SCSI clock
10 D2 Coma Mode
11 D3 Minimum Power