Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
11.4.4 _CRT (Critical Temperature)
This object, when defined under a thermal zone, returns the critical temperature at which OSPM
must shutdown the system. If this object it present under a device, the device’s driver evaluates this
object to determine the device’s critical cooling temperature trip point. This value may then be used
by the device’s driver to program an internal device temperature sensor trip point.
Arguments:
None
Return Value:
An Integer containing the critical temperature threshold in tenths of degrees Kelvin
The result is an integer value that represents the critical shutdown threshold in tenths of degrees. For
example, 300.0K is represented by the integer 3000.
11.4.5 _CR3 (Warm/Standby Temperature)
This object, when defined under a thermal zone, returns the critical temperature at which OSPM may
choose to transition the system into a low power state with a faster exit latency than S4 sleeping state
(e.g. S3, or an equivalent low power state if the LOW_POWER_S0_IDLE_CAPABLE FADT flag
is set). The platform vendor should define _CR3 to be sufficiently below _CRT so as to allow
enough time to transition the system into this low power state. It may be sufficient to define either
_CR3 or _HOT depending on the type and thermal characteristics of the specific thermal zone under
consideration. If this object it present under a device, the device’s driver evaluates this object to
determine the device’s warm/standby cooling temperature trip point. This value may then be used by
the device’s driver to program an internal device temperature sensor trip point.
Arguments:
None
Return Value:
An Integer containing the critical temperature threshold in tenths of degrees Kelvin
The result is an integer value that represents the critical shutdown threshold in tenths of degrees. For
example, 300.0K is represented by the integer 3000.
11.4.6 _DTI (Device Temperature Indication)
This optional object may be present under a device and is evaluated by OSPM when the device’s
native (driver managed) temperature sensor has crossed a cooling temperature trip point or when a
meaningful change in temperature (as indicated by evaluation of the _NTT object) has occurred.
OSPM evaluation of the _DTI object enables the platform to take action as a result of these events.
For example, the platform may choose to implement fan control hysteresis based on the conveyed
value or signal the revaluation of the _TDL or _PDL objects.
Arguments: (1)
Arg0 – An Integer containing the current value of the temperature sensor (in tenths Kelvin)
612 April, 2015 Version 6.0