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From:   Varun Sethi <V.Sethi@nxp.com>
To:     Fabio Estevam <festevam@gmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>
CC:     Horia Geanta <horia.geanta@nxp.com>,
        Gaurav Jain <gaurav.jain@nxp.com>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@vger.kernel.org>, Fabio Estevam <festevam@denx.de>
Subject: RE: [EXT] Re: [PATCH v2] crypto: caam - fix i.MX6SX entropy delay
 value
Thread-Topic: [EXT] Re: [PATCH v2] crypto: caam - fix i.MX6SX entropy delay
 value
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Date:   Sat, 16 Apr 2022 18:05:13 +0000
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Hi Fabio,
Just responded to the patch posted by you. For i.MX6D I will check with the=
 hardware IP team. As mentioned in the earlier thread we will be passing th=
e entropy delay value via device tree property.


Regards
Varun

> -----Original Message-----
> From: Fabio Estevam <festevam@gmail.com>
> Sent: Saturday, April 16, 2022 8:04 PM
> To: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: Horia Geanta <horia.geanta@nxp.com>; Gaurav Jain
> <gaurav.jain@nxp.com>; Varun Sethi <V.Sethi@nxp.com>; open list:HARDWARE
> RANDOM NUMBER GENERATOR CORE <linux-crypto@vger.kernel.org>; Fabio
> Estevam <festevam@denx.de>
> Subject: [EXT] Re: [PATCH v2] crypto: caam - fix i.MX6SX entropy delay va=
lue
>=20
> Caution: EXT Email
>=20
> Hi Horia and Varun,
>=20
> On Sat, Apr 16, 2022 at 10:54 AM Fabio Estevam <festevam@gmail.com> wrote=
:
> >
> > From: Fabio Estevam <festevam@denx.de>
> >
> > Since commit 358ba762d9f1 ("crypto: caam - enable prediction
> > resistance in HRWNG") the following CAAM errors can be seen on i.MX6SX:
> >
> > caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: Hardware error
> > hwrng: no data available
> > caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: Hardware error
> > ...
> >
> > This error is due to an incorrect entropy delay for i.MX6SX.
> >
> > Fix it by increasing the minimum entropy delay for i.MX6SX as done in
> > U-Boot:
> > https://eur01.safelinks.protection.outlook.com/?url=3Dhttps%3A%2F%2Fpat=
c
> >
> hwork.ozlabs.org%2Fproject%2Fuboot%2Fpatch%2F20220415111049.2565744-
> 1-
> >
> gaurav.jain%40nxp.com%2F&amp;data=3D04%7C01%7CV.Sethi%40nxp.com%7C9
> 6c829
> >
> a14c394eb5e20508da1fb62811%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0
> %7C1%
> >
> 7C637857164474600314%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwM
> DAiLCJQI
> >
> joiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=3DjKZQyH0q
> Z50
> > rZhRV6%2FtOgkacpQZ9pZnwo6dLEkMUARs%3D&amp;reserved=3D0
> >
> > Signed-off-by: Fabio Estevam <festevam@denx.de>
> > ---
> > Change since v1:
> > - Align the fix with U-Boot.
>=20
> Actually, after thinking more about it, I realize that this issue is not =
i.MX6SX
> specific as I have seen reports of the same failures on i.MX6D as well.
>=20
> Would it make sense to fix it like this instead?
>=20
> --- a/drivers/crypto/caam/regs.h
> +++ b/drivers/crypto/caam/regs.h
> @@ -516,7 +516,7 @@ struct rng4tst {
>         };
>  #define RTSDCTL_ENT_DLY_SHIFT 16
>  #define RTSDCTL_ENT_DLY_MASK (0xffff << RTSDCTL_ENT_DLY_SHIFT) -
> #define RTSDCTL_ENT_DLY_MIN 3200
> +#define RTSDCTL_ENT_DLY_MIN 12000
>  #define RTSDCTL_ENT_DLY_MAX 12800
>         u32 rtsdctl;            /* seed control register */
>         union {
>=20
> Any drawbacks in using this generic approach?
>=20
> Please advise.