linux-kernel - Re: [PATCH v1] crypto: caam

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Message-ID: <20170719163248.sn7mvnq2s3fm2hvh@pengutronix.de>
Date:   Wed, 19 Jul 2017 18:32:49 +0200
From:   Oleksij Rempel <ore@...gutronix.de>
To:     Horia Geantă <horia.geanta@....com>
Cc:     Oleksij Rempel <o.rempel@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        Dan Douglass <dan.douglass@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] crypto: caam - set hwrng quality level

On Wed, Jul 19, 2017 at 12:49:47PM +0000, Horia Geantă wrote:
> On 7/19/2017 10:45 AM, Oleksij Rempel wrote:
> > According documentation, it is NIST certified TRNG.
> > So, set high quality to let the HWRNG framework automatically use it.
> > 
> > Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> > ---
> >  drivers/crypto/caam/caamrng.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c
> > index 41398da3edf4..684c0bc88dfd 100644
> > --- a/drivers/crypto/caam/caamrng.c
> > +++ b/drivers/crypto/caam/caamrng.c
> > @@ -292,10 +292,16 @@ static int caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev)
> >  	return 0;
> >  }
> >  
> > +/*
> > + * hwrng register struct
> > + * The trng is suppost to have 100% entropy, and thus
> > + * we register with a very high quality value.
> > + */
> >  static struct hwrng caam_rng = {
> >  	.name		= "rng-caam",
> >  	.cleanup	= caam_cleanup,
> >  	.read		= caam_read,
> > +	.quality	= 999,
> 
> Why not 1024, i.e. where is 999 coming from?

It comes from s390-trng.c driver.
Should I use 1024 instead?

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