• Haavard Skinnemoen's avatar
    atmel-mci: Add experimental DMA support · 65e8b083
    Haavard Skinnemoen authored
    This adds support for DMA transfers through the generic DMA engine
    framework with the DMA slave extensions.
    
    The driver has been tested using mmc-block and ext3fs on several SD,
    SDHC and MMC+ cards. Reads and writes work fine, with read transfer
    rates up to 7.5 MiB/s on fast cards with debugging disabled.
    
    Unfortunately, the driver has been known to lock up from time to time
    with DMA enabled, so DMA support is currently optional and marked
    EXPERIMENTAL. However, I didn't see any problems while testing 13
    different cards (MMC, SD and SDHC of different brands and sizes), so I
    suspect the "Initialize BLKR before sending data transfer command" fix
    that was posted earlier fixed this as well.
    Signed-off-by: default avatarHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
    65e8b083
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