TDA4VM: QSPI flash program wrong data into nor flash

Part Number: TDA4VM
Other Parts Discussed in Thread: DRA829,

Hi, expert:

#1 background:

chip used: dra829/TDA4VM

norflash used: MT25QU128ABA8E12-0AAT

OSPI CONFIG

#elif defined(j721e_evm)
    OSPI_v0_HwAttrs ospi_cfg;

    /* Get the default OSPI init configurations */
    OSPI_socGetInitCfg(BOARD_OSPI_NOR_INSTANCE/*BOARD_SPI_NOR_INSTANCE*/, &ospi_cfg);
    ospi_cfg.intrEnable = false;
    /* Enable quad mode */
    ospi_cfg.xferLines = OSPI_XFER_LINES_QUAD;
    // ospi_cfg.phyEnable = false;
    ospi_cfg.dmaEnable = false;
    ospi_cfg.dtrEnable = false;
    //ospi_cfg.dacEnable = false;
    // ospi_cfg.funcClk = (80000000U);
    ospi_cfg.blkSize = 16;

    /* Set the default SPI init configurations */
    OSPI_socSetInitCfg(BOARD_OSPI_NOR_INSTANCE/*BOARD_SPI_NOR_INSTANCE*/, &ospi_cfg);

    /* Open the Board QSPI NOR device */
    gQspiHandle = Board_flashOpen(QSPI_FLASH_ID,
                                  BOARD_OSPI_NOR_INSTANCE/*BOARD_SPI_NOR_INSTANCE*/, NULL);

#else

now i want to program our nor flash by ospi controller, 

at first i tried to program the following sample patterns

0x00 0x01 0x02...0xFF(256 repeated)

but when i set 

but while i set ospi_cfg.dacEnable = false, the flash content is same as i expected.

so the question is why this DAC config option will caused this phenomenon?

Regards.

yan