SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
Low power modes can be initiated by software when there are no pending transactions, but the SATA AHCI core also supports aggressive power management. In this mode, the subsystem automatically initiates the PARTIAL or SLUMBER state when there are no inflight commands. This is useful for power savings, but the price is increased latency if a low-power mode is entered and a transfer request is made. Software enables aggressive link-layer power management by setting the SATA_PxCMD[26]ALPE bit to 0x1. The link aggressive power management state (PARTIAL or SLUMBER) is selected using the SATA_PxCMD[27]ASP bit.