EP80579 Datasheet, PDF (889/1916 Pages) Intel Corporation – Intel® EP80579 Integrated Processor Product Line

Intel^® EP80579 Integrated Processor
23.6.4
23.6.4.1
23.6.4.2
Power Management Operation
Introduction
This section covers power management of the HBA and the Serial ATA interface. This
specification does not cover any power management that a Serial ATA device may do
internally that is transparent to the interface.
Power State Mappings
The PCI specification defines power management states for devices, which shall be
applied to the HBA. They are:
• D0 - Working (required).
• D1 - Not defined for storage HBAs.
• D2 - Not defined for storage HBAs.
• D3 - Very deep sleep (required). This state is split into two sub-states, D3HOT (can
respond to PCI configuration accesses) and D3COLD (cannot respond to PCI
configuration accesses). These two sub-states are considered the same, where
D3HOT has VCC, but D3COLD does not. PxCMD.ST must be cleared to '0' before
entering the D3 power state.
Serial ATA devices may also have multiple power states. Each of these device states are
subsets of the HBA's D0 state. They are:
• D0 - Device is working and instantly available.
• D1 - Device enters when it receives a STANDBY IMMEDIATE command. Exit latency
from this state is in seconds.
• D2 - Not currently defined for Serial ATA devices.
• D3 - Device enters when it receives a SLEEP command. Exit latency from this state
is in seconds.
Finally, Serial ATA defines three Phy layer (or interface) power states. They are:
• Phy Ready - Phy logic and PLL are both on and active.
• Partial - Phy logic is powered, but in a reduced state. Exit latency is no longer than
10µs.
• Slumber - Phy logic is powered, but in a reduced state. Exit latency can be up to
10ms.
Since these states have much lower exit latency than the D1 and D3 states, AHCI
defines these states as sub-states of the device D0 state.
The following picture gives a hierarchical view of power states of Serial ATA.
August 2009
Order Number: 320066-003US
Intel^® EP80579 Integrated Processor Product Line Datasheet
889