Re: [PATCH 3/3] crypto: Add Allwinner Security System crypto accelerator

Herbert Xu
2014-07-23T13:58:20Z

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.

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