FIC M296 - Manual (Page 78)

Software Functional Overview
An optimally designed system that uses several SCI events can notify the OS of thermal
increase or decrease by raising an interrupt every several degrees. This enables the OS to
anticipate _ACx, PSV, or _CRT events and incorporate heuristics to better manage the
systems temperature.The operating system can request that the hardware change the priority
of active cooling vs passive cooling.
z Dynamically Changing Cooling Temperatures
An OEM can reset _ACx and _PSV and notify the OS to reevaluate the control methods to
retrieve the new temperature settings. The following three causes are the primary uses for this
thermal notification:
− When a user changes from one cooling mode to the other.
− When a swappable bay device is inserted or removed. A swappable bay is a slot that
can accommodate several different devices that have identical form factors, such as a
CD-ROM drive, disk drive, and so on. Many mobile PCs have this concept already in
place.
− When the temperature reaches an _ACx or the _PSV policy settings
In each situation, the OEM-provided AML code must execute a Notify ( thermal_zone, 0x80)
statement to request the OS to re-evaluate each policy temperature by running the _PSV and
_ACx control methods.
„ Resetting Cooling Temperatures from the User Interface
When the user employs the UI to change from one cooling mode to the other, the
following occurs:
1. The OS notifies the hardware of the new cooling mode by running the Set
Cooling Policy (_SCP) control method.
2. When the hardware receives the notification, it can set a new temperature
for both cooling policies and notify the OS that the thermal zone policy
temperatures have changed.
3. The OS re-evaluates _PSV and _ACx.
„ Resetting Cooling Temperatures to Adjust to Bay Device
Insertion or Removal
The hardware can adjust the thermal zone temperature to accommodate the
maximum operating temperature of a bay device as necessary. For example,
1. Hardware detects that a device was inserted into or removed from the bay
and resets the _PSV and/or _ACx and then notifies the OS of the thermal
and device insertion events.
2. The OS reenumerates the devices and reevaluates _PSV and _ACx.
„ Resetting Cooling Temperatures to Implement Hysteresis
An OEM can build hysteresis into platform thermal design by dynamically
3-28
FIC M295 / M296 Service Manual