RCR_MFB_SHIFT
#define RCR_MFB_2K (0U << RCR_MFB_SHIFT)
#define RCR_MFB_4K (1U << RCR_MFB_SHIFT)
#define RCR_MFB_8K (2U << RCR_MFB_SHIFT)
#define RCR_MFB_16K (3U << RCR_MFB_SHIFT)