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    SubjectRe: [PATCH 2.6-git] SPI core refresh

    --- Vitaly Wool <vwool@ru.mvista.com> wrote:

    > Greetings,
    >
    > This is an updated version of SPI framework developed by Dmitry Pervushin and Vitaly Wool.
    >
    > The main changes are:
    >
    > - Matching rmk's 2.6.14-git5+ changes for device_driver suspend and resume calls
    > - The character device interface was reworked
    >
    > I still think that we need to continue converging with David Brownell's core, despite some
    > misalignments happening in the email exchange :). Although it's not yet done in our core, I plan
    > to move to
    > - using chained SPI messages as David does
    > - maybe rework the SPI device interface more taking David's one as a reference
    >
    > However, there also are some advantages of our core compared to David's I'd like to mention
    >
    > - it can be compiled as a module
    So can David's. You can use BIOS tables in which case you must compile the SPI core into the
    kernel but you can also use spi_new_device which allows the SPI core to be built as a module (and
    is how I am using it).

    > - it is DMA-safe
    To my understanding David's core is DMA-safe. Yes there is a question mark over one of the helper
    functions, but the _main_ functions _are_ DMA-safe.

    > - it is priority inversion-free
    > - it can gain more performance with multiple controllers
    Sorry I'm not sure what you mean here.

    > - it's more adapted for use in real-time environments
    > - it's not so lightweight, but it leaves less effort for the bus driver developer.

    But also less flexibility. A core layer shouldn't _force_ a policy
    on a bus driver. I am currently developing an adapter driver for David's system and I wouldn't say
    that the core is making me do things I think the core should do. Please could you provide examples
    of where you think Davids SPI core requires 'effort'.

    Mark






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