Attached memory test can be used to test DDR memory (or any other memory type or memory mapped peripheral) on ADSP-2156x processor. The test is performed for different types of accesses (e.g., core, DMA, 8-/16-/32-/64-bit) and different data patterns (for example, all 0x0, all 0xF, all 0x5, all 0xA, incremental, random, and all bits toggling).
Also, please refer the EE-387, which is for Interfacing DDR3/DDR2/LPDDR Memory to ADSP-SC58x/2158x Processors.