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    SubjectRe: [PATCH 4/7] mmc: at91_mci: add multiwrite switch
    On Fri, May 30, 2008 at 02:08:56PM +0200, Nicolas Ferre wrote:
    > at91_mci is capable of multiwrite. Enable it before it disappears.

    This doesn't look safe. MULTIWRITE is not about whether you can do
    multi-writes, but whether you can properly report how many bytes were
    successfully written to the card _and_ the card acknowledged as having
    been successfully written.

    It looks to me as if the AT91 MMC driver reports no bytes, or all
    bytes if the FIFO reports that it became empty, which presumably it
    may do if you're unable to keep the FIFO full?

    (Dropped Hans-JA¼rgen from the CC list since my mailer seems to corrupt
    the address.)

    If Pierre wants to remove the MULTIWRITE flag, I'd like to hear his
    solution for the pxamci driver, where the only way to ascertain how
    many bytes were transmitted may be to walk the SG list comparing the
    DMA pointer with what was in the hardware DMA engine at the time.
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