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    SubjectRe: New MMC maintainer needed
    On Fri, 31 Jul 2009 11:54:07 +0100
    Matt Fleming <> wrote:

    > On Fri, Jul 31, 2009 at 12:26:23PM +0200, Pierre Ossman wrote:
    > >
    > > [PATCH 0/32] mmc and omap_hsmmc patches
    > >
    > >
    > > I haven't looked through these at all. The ones affecting the core
    > > probably need some thorough reviews.
    > >
    > > I did notice the patch to say which cards a controller supports though,
    > > and I'm very sceptical about that one. The scanning process should work
    > > anyway, and the performance impact should be negligible as it is only
    > > on init. So that patch only adds complexity and confusion IMO.
    > >
    > How much complexity does it really add? Surely it's better to give the
    > host controller driver writers the ability to not entertain supporting
    > some cards if they cannot be used? If they want to avoid the scanning
    > process for certain cards, why not let them?

    Let's look at the pros and cons of this:


    - The scanning code gets less clear as you increase the number of
    possible paths through it.

    - Different systems will have different init sequences, possibly
    provoking bugs in the cards.

    - Host driver writers now have more capability bits they have to
    consider. And these might be less than obvious since SD/MMC/SDIO are
    normally compatible so these bits seem useless.

    - With the current logic (which was better in the first version),
    "normal" drivers will have to explicitly state that they work as
    intended by setting all bits.


    - A slightly reduced scanning time.

    I simply don't see it as being worth it. Linux patches generally need
    to provide the answer to "Why?", not just be able to avoid "Why not?".

    -- Pierre Ossman

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