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From:   Horia Geanta <horia.geanta@nxp.com>
To:     Andrey Smirnov <andrew.smirnov@gmail.com>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>
CC:     Chris Healy <cphealy@gmail.com>,
        Lucas Stach <l.stach@pengutronix.de>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Iuliana Prodan <iuliana.prodan@nxp.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        dl-linux-imx <linux-imx@nxp.com>,
        Andrei Botila <andrei.botila@nxp.com>,
        Laurentiu Tudor <laurentiu.tudor@nxp.com>
Subject: Re: [PATCH v6 0/7] enable CAAM's HWRNG as default
Thread-Topic: [PATCH v6 0/7] enable CAAM's HWRNG as default
Thread-Index: AQHVxjopojbABEfYu0izDuntHRvy8g==
Date:   Wed, 22 Jan 2020 15:11:51 +0000
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References: <20200108154047.12526-1-andrew.smirnov@gmail.com>
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On 1/8/2020 5:41 PM, Andrey Smirnov wrote:=0A=
> Everyone:=0A=
> =0A=
> This series is a continuation of original [discussion]. I don't know=0A=
> if what's in the series is enough to use CAAMs HWRNG system wide, but=0A=
> I am hoping that with enough iterations and feedback it will be.=0A=
> =0A=
Testing on DPAA2-based Layerscape platforms, for e.g. LS1088A:=0A=
[...]=0A=
[   12.379136] caam_jr 8010000.jr: 20000256: CCB: desc idx 2: RNG: Predicti=
on resistance=0A=
[   12.387036] hwrng: no data available=0A=
[...]=0A=
=0A=
caamrng driver fails, because RNG initialization is skipped=0A=
in ctrl.c - caam_probe():=0A=
	[...]=0A=
	np =3D of_find_compatible_node(NULL, NULL, "fsl,qoriq-mc");=0A=
	ctrlpriv->mc_en =3D !!np;=0A=
	[...]=0A=
	/*=0A=
	 * If SEC has RNG version >=3D 4 and RNG state handle has not been=0A=
	 * already instantiated, do RNG instantiation=0A=
	 * In case of SoCs with Management Complex, RNG is managed by MC f/w.=0A=
	 */=0A=
	if (!ctrlpriv->mc_en && rng_vid >=3D 4) {=0A=
	[...]=0A=
=0A=
NXP is working at adding RNG Prediction Resistance support in MC f/w=0A=
(will be available in v10.20.1).=0A=
=0A=
However, there's a backwards-compatibility requirement: kernel should work=
=0A=
with older MC f/w versions.=0A=
To fix this, my suggestion is to force RNG (re)initialization in case=0A=
MC f/w is present and its version is < 10.20.1, i.e.:=0A=
	if ((!ctrlpriv->mc_en || (fsl_mc_get_version() < "10.20.1")) &&=0A=
	    rng_vid >=3D 4) {=0A=
	[...]=0A=
=0A=
fsl_mc_get_version() - I've made this up, it currently doesn't exist,=0A=
it should be added in fsl-mc bus driver (drivers/bus/fsl-mc).=0A=
We will provide this shortly, the plan being to integrate this change=0A=
as part of this series.=0A=
=0A=
Thanks,=0A=
Horia=0A=