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DM3730 hsmmc driver DMA vs PIO mode

Hi, guys., i recently encounter a big problem. When i write a big file to SD card, then i read it again and compare it with the original file, it make difference!!!  Some bytes change.

After i change the hsmmc driver, use PIO mode instead of DMA mode.  The errors disappear!!!  Is it the ddr problem or hsmmc driver problem?


I also test file in nand or usb mass storage, there are no errors also.

PS:

CPU: DM3730-CUS

KERNEL: based on rowboat, 2.6.32

DDR: micron MCP MT29C4G96MAZAPCJA-5(512MB nand flash + 512MB LPDDR)