Registers
1397
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Serial ATA (SATA) Controller
Table 28-28. Port Command Register (P0CMD) Field Descriptions (continued)
Bit
Field
Value
Description
1
SUD
0-1
Spin-Up Device. This bit is read/write if staggered spin-up is supported as indicated by the CAP.SSS =
1. This bit is read-only 1 if staggered spin-up is not supported and CAP.SSS = 0. On an edge detect
from 0 to 1, the Port starts a COMRESET initialization sequence to the device. Clearing this bit causes
no action on the interface.
Note: the SUD bit is read-only 0 on power-up until CAP.SSS bit is written with the required value.
0
ST
0-1
Start. When set to 1, the Port processes the command list. When cleared, the Port does not process the
command list. Whenever this bit is changed from a 0 to a 1, the Port starts processing the command list
at entry 0. Whenever this bit is changed from a 1 to a 0, the P0CI register is cleared by the Port upon
transition into an idle state. Refer to the AHCI specification for important restrictions on when this bit can
be set to 1.