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Subject: Re: [PATCH v5 13/15] crypto: iaa - Add support for default IAA
 'canned' compression mode
From:   Tom Zanussi <tom.zanussi@linux.intel.com>
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     davem@davemloft.net, fenghua.yu@intel.com, vkoul@kernel.org,
        dave.jiang@intel.com, tony.luck@intel.com,
        wajdi.k.feghali@intel.com, james.guilford@intel.com,
        kanchana.p.sridhar@intel.com, giovanni.cabiddu@intel.com,
        linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
        dmaengine@vger.kernel.org
Date:   Tue, 30 May 2023 14:50:03 -0500
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Hi Herbert,

On Thu, 2023-05-25 at 08:37 +0800, Herbert Xu wrote:
> On Wed, May 24, 2023 at 10:58:54AM -0500, Tom Zanussi wrote:
> >=20
> > Yes, I think you're right.=C2=A0 The reason we did it this way was that
> > we're expecting to add more modes, such as 'dynamic' and/or
> > 'canned-
> > dynamic' etc.
> >=20
> > But I don't see a reason we couldn't just register them all and
> > have
> > the user choose using the algorithm names, especially if that's the
> > way
> > crypto users expect things to work.
>=20
> Are these modes compatible with the deflate algorithm, that is,
> can the generic deflate uncompress the output of these modes and
> vice versa, can these modes uncompress the output of the generic
> algorithm?
>=20
> If they're all compatible, then you should just use the "deflate"
> algorithm name and use different driver names to differentiate them.
> But if they're not compatible then the modes should have distinct
> algorithm names.

Canned mode is not compatible with generic deflate.  Fixed mode is, but
due to history-window limitations in the hardware, only for buffers <=3D
4k, or that have been compressed using a <=3D 4k history window.

So it sounds like we need to use distinct algorithm names, which I'll
add in the next version.

Thanks,

Tom=20


>=20
> Cheers,