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    SubjectRe: sdio: enhance IO_RW_EXTENDED support
    Pierre Ossman wrote:
    > On Tue, 31 Jul 2007 16:36:30 +0100
    > David Vrabel <> wrote:
    >> These three patches enhance the support for the SDIO IO_RW_EXTENDED
    >> command. The block size of functions is managed and the I/O ops
    >> (sdio_readsb() etc) are extended to handle arbitrary lengths of data
    >> (by using multiple commands).
    >> I've not yet had a chance to test this stuff as I don't (yet) have
    >> the time to write a Bluetooth Type-A driver so these are posted as an
    >> example of the sort of API I'd expect.
    > Thanks. These are some nice improvements. I do have one suggestion
    > though:
    > Could we design it so that sdio_io_rw_ext_helper() sets the block size
    > itself? That way most drivers wouldn't have to care about that detail
    > and the core would be free to choose optimal values.

    I would expect the block size to be set once per card, and never be
    changed and thus it's not logically a per-transfer operation. We
    certainly wouldn't want to change the block size willy-nilly as it's an
    expensive operation.

    The patch I've presented does put the selection of the block size in the
    core (bar one thing which I agree should be removed).

    > I suspect that some transactions might require a certain block size.
    > But we could satisfy that by stating that any transfer small enough to
    > fit into one block will not be split up.

    I consider it unlikely that any card would want to do anything other
    than always use the largest possible block size.

    David Vrabel, Software Engineer, Drivers group Tel: +44 (0)1223 692562
    CSR plc, Churchill House, Cambridge Business Park, Cowley Road, CB4 0WZ

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