Advanced Configuration and Power Interface Specification

Power and Performance Management
If the device can wake the system from the S4 system sleeping state (see _PRW) then the device
must support wake in the D-state returned by this object. However, OSPM cannot assume wake from
the S4 system sleeping state is supported in any deeper D-state unless specified by a corresponding
_S4W object. The table below provides a mapping from Desired Actions to Resultant D-state
entered based on the values returned from the _S4D, _PRW, and _S4W objects if they exist . (D/C
means Don’t Care – evaluation is irrelevant, and N/A means Non Applicable – object does not
exist).
Table 7-233 S4 Action / Result Table
Desired Action _S4D _PRW _S4W Resultant D-state
Enter S4 N/A D/C N/A OSPM decides
Enter S4, No Wake 2 D/C D/C Enter D2 or D3
Enter S4, Wake 2 4 N/A Enter D2
Enter S4, Wake 2 4 3 Enter D2 or D3
Enter S4, Wake N/A 4 2 Enter D0, D1 or D2
7.3.20 _S0W (S0 Device Wake State)
This object evaluates to an integer that conveys to OSPM the deepest D-state supported by this
device in the S0 system sleeping state where the device can wake itself.
Arguments:
None
Return Value:
An Integer containing the deepest D-state that supports wake in state S0. If OSPM has not indicated
that it supports _PR3 through the OSPM Platform-Wide Capabilities (see Section 6.2.11.2), then the
value "3" corresponds to D3. If it has indicated _PR3 support, the value "3" represents D3hot and
the value "4" represents D3cold.
_S0W must return the same integer each time it is evaluated. This value allows OSPM to choose the
deepest power D-state and still achieve wake functionality. If object evaluates to zero, then the
device cannot wake itself from any deeper D state.
7.3.21 _S1W (S1 Device Wake State)
This object evaluates to an integer that conveys to OSPM the deepest D-state supported by this
device in the S1 system sleeping state that can wake the system.
Arguments:
None
Return Value:
An Integer containing the deepest D-state that supports wake in state S1. If OSPM has not indicated
that it supports _PR3 through the OSPM Platform-Wide Capabilities (see Section 6.2.11.2), then the
value "3" corresponds to D3. If it has indicated _PR3 support, the value "3" represents D3hot and
the value "4" represents D3cold.
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