SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
[New DRA7xxP feature versus DRA75x/DRA74x]
The Read-Modify-Write (RMW) module is placed between the Bus Arbiter and the internal Command FIFO logic of the EMIF such that multi-quanta writes can be used even though system masters write sub-quanta of data. A quanta is defined as 2 bytes in narrow mode and 4 bytes in wide mode. Any sub-quanta write is converted into a RMW of aligned SDRAM burst size (32 bytes). The RMW module does not affect normal aligned ECC block read or write bursts. Any sub-quanta writes, although turned into RMW operation, maintain full coherency. When RMW is enabled (EMIF_ECC_CTRL_REG[31] REG_ECC_EN = 0x1 and EMIF_ECC_CTRL_REG[28] REG_RMW_EN = 0x1), all sub-quanta writes to nonregister space are converted into a RMW operation of SDRAM burst size.