SATA Controller Registers (D31:F5)
638 Datasheet
15.3.2.2 PxSCTL — Serial ATA Control Register (D31:F5)
Address Offset: Attribute: R/W, RO
Default Value: 00000004h Size: 32 bits
SDATA when SINDX.RIDX is 01h. This is a 32-bit read-write register by which software
controls SATA capabilities. Writes to the SControl register result in an action being
taken by the PCH or the interface. Reads from the register return the last value written
to it.
Bit Description
31:20 Reserved
19:16 Port Multiplier Port (PMP) — RO. This field is not used by AHCI.
15:12 Select Power Management (SPM) — RO. This field is not used by AHCI.
11:8
Interface Power Management Transitions Allowed (IPM) — R/W. Indicates which
power states the PCH is allowed to transition to:
All other values reserved
7:4
Speed Allowed (SPD) — R/W. Indicates the highest allowable speed of the interface.
This speed is limited by the CAP.ISS (ABAR+00h:bit 23:20) field.
All other values reserved.
The PCH Supports Gen 1 communication rates (1.5 Gb/s), Gen 2 rates
(3.0 Gb/s)
3:0
Device Detection Initialization (DET) — R/W. Controls the PCH’s device detection
and interface initialization.
All other values reserved.
When this field is written to a 1h, the PCH initiates COMRESET and starts the
initialization process. When the initialization is complete, this field shall remain 1h until
set to another value by software.
This field may only be changed to 1h or 4h when PxCMD.ST is 0. Changing this field
while the PCH is running results in undefined behavior.
Value Description
0h No interface restrictions
1h Transitions to the PARTIAL state disabled
2h Transitions to the SLUMBER state disabled
3h Transitions to both PARTIAL and SLUMBER states disabled
Value Description
0h No speed negotiation restrictions
1h Limit speed negotiation to Generation 1 communication rate
2h Limit speed negotiation to Generation 2 communication rate
Value Description
0h No device detection or initialization action requested
1h
Perform interface communication initialization sequence to
establish communication. This is functionally equivalent to a hard
reset and results in the interface being reset and communications
re-initialized
4h Disable the Serial ATA interface and put Phy in offline mode
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