35.5.4.4 DDR3 Device DLL On/Off Switching Procedure
The JEDEC standard allows switching between DLL Off and DLL On modes, and hence beetwen low and high frequencies.
To enable DDR3 DLL Off mode, set MPDDRC_CR.DIS_DLL to 1. To enable DDR3 DLL On mode, set MPDDRC_CR.DIS_DLL to 0 during DDR3-SDRAM initialization.