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    SubjectRe: [PATCH 3/3] crypto: Add Allwinner Security System crypto accelerator
    On Wed, Jul 23, 2014 at 04:07:20PM +0200, Marek Vasut wrote:
    > On Wednesday, July 23, 2014 at 03:57:35 PM, Herbert Xu wrote:
    > > On Sat, May 24, 2014 at 02:00:03PM +0200, Marek Vasut wrote:
    > > > > + }
    > > > > +#endif
    > > > > +
    > > > > +#ifdef CONFIG_CRYPTO_DEV_SUNXI_SS_MD5
    > > > > + err = crypto_register_shash(&sunxi_md5_alg);
    > > >
    > > > Do not use shash for such device. This is clearly and ahash (and async in
    > > > general) device. The rule of a thumb here is that you use sync algos only
    > > > for devices which have dedicated instructions for computing the
    > > > transformation. For devices which are attached to some kind of bus, you
    > > > use async algos (ahash etc).
    > >
    > > I'm sorry that I didn't catch this earlier but there is no such
    > > rule.
    > >
    > > Unless you need the async interface you should stick to the sync
    > > interfaces for the sake of simplicity.
    > >
    > > We have a number of existing drivers that are synchronous but
    > > using the async interface. They should either be converted
    > > over to the sync interface or made interrupt-driven if possible.
    >
    > Sure, but this device is interrupt driven and uses DMA to feed the crypto
    > engine, therefore async, right ?

    If it's interrupt-driven, then yes it would certainly make sense to
    be async. But all I see is polling in the latest posting, was the
    first version different?

    Cheers,
    --
    Email: Herbert Xu <herbert@gondor.apana.org.au>
    Home Page: http://gondor.apana.org.au/~herbert/
    PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt


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