Advanced Configuration and Power Interface Specification

ACPI-Defined Devices and Device-Specific Objects
ATA task file array definition:
• Seven register values for command 1
— Reg values: (1F1, 1F2, 1F3, 1F4, 1F5, 1F6, 1F7)
• Seven register values for command 2
— Reg values: (1F1, 1F2, 1F3, 1F4, 1F5, 1F6, 1F7)
• Seven register values for command 3
— Reg values: (1F1, 1F2, 1F3, 1F4, 1F5, 1F6, 1F7)
• Etc.
After powering up the drive, OSPM will send these commands to the drive, in the order specified.
On SATA HBAs, OSPM evaluates _SDD before evaluating _GTF. The IDE driver may modify
some of the feature commands or append its own to better tune the drive for OSPM features before
sending the commands to the drive.
This Control Method is listed under each drive device object. OSPM must evaluate the _STM object
or the _SDD object before evaluating the _GTF object.
Example of the return from _GTF:
Method(_GTF, 0x0, NotSerialized)
{
Return(GTF0)
}
Name(GTF0, Buffer(0x1c)
{
0x03, 0x00, 0x00, 0x00, 0x00, 0xa0, 0xef, 0x03, 0x00, 0x00, 0x00, 0x00,
0xa0, 0xef, 0x00, 0x10, 0x00, 0x00, 0x00, 0xa0, 0xc6, 0x00, 0x00, 0x00,
0x00, 0x00, 0xa0, 0x91
}
9.8.2 IDE Controller Device
Most device drivers can save and restore the registers of their device. For IDE controllers and drives,
this is not true because there are several drive settings for which ATA does not provide mechanisms
to read. Further, there is no industry standard for setting timing information for IDE controllers.
Because of this, ACPI interface mechanisms are necessary to provide the operating system
information about the current settings for the drive and channel, and for setting the timing for the
channel.
OSPM and the IDE driver will follow these steps when powering off the IDE subsystem:
1. The IDE driver will call the _GTM control method to get the current transfer timing settings for
the IDE channel. This includes information about DMA and PIO modes.
2. The IDE driver will call the standard OS services to power down the drives and channel.
3. As a result, OSPM will execute the appropriate _PS3 methods and turn off unneeded power
resources.
To power on the IDE subsystem, OSPM and the IDE driver will follow these steps:
1. The IDE driver will call the standard OS services to turn on the drives and channel.
2. As a result, OSPM will execute the appropriate _PS0 methods and turn on required power
resources.
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