Re: [PATCH v7 0/3] hwrng: add hwrng support for Rockchip RK3568

From: Daniel Golle <daniel@makrotopia.org>
To: Diederik de Haas <didi.debian@cknow.org>
Cc: "Chen-Yu Tsai" <wens@kernel.org>,
	linux-rockchip@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	"Rob Herring" <robh@kernel.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	linux-kernel@vger.kernel.org,
	"Herbert Xu" <herbert@gondor.apana.org.au>,
	"Martin Kaiser" <martin@kaiser.cx>,
	"Sascha Hauer" <s.hauer@pengutronix.de>,
	"Sebastian Reichel" <sebastian.reichel@collabora.com>,
	"Ard Biesheuvel" <ardb@kernel.org>,
	"Uwe Kleine-König" <ukleinek@debian.org>,
	devicetree@vger.kernel.org, linux-crypto@vger.kernel.org,
	"Philipp Zabel" <p.zabel@pengutronix.de>,
	"Olivia Mackall" <olivia@selenic.com>,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
	"Dragan Simic" <dsimic@manjaro.org>,
	"Aurelien Jarno" <aurelien@aurel32.net>,
	"Heiko Stuebner" <heiko@sntech.de>,
	"Anand Moon" <linux.amoon@gmail.com>
Subject: Re: [PATCH v7 0/3] hwrng: add hwrng support for Rockchip RK3568
Date: Wed, 17 Jul 2024 03:24:55 +0100	[thread overview]
Message-ID: <ZpcrdwZBNFu-YlZt@makrotopia.org> (raw)
In-Reply-To: <3220752.Q7WYUMVHaa@bagend>

On Tue, Jul 16, 2024 at 07:19:35PM +0200, Diederik de Haas wrote:
> On Tuesday, 16 July 2024 18:53:43 CEST Diederik de Haas wrote:
> > rngtest: FIPS 140-2(2001-10-10) Long run: 0
> 
> I don't know if it means something, but I noticed that I have
> ``Long run: 0`` with all my poor results,
> while Chen-Yu had ``Long run: 1``.
> 
> Different SoC (RK3399), but Anand had ``Long run: 0`` too on their
> very poor result (100% failure):
> https://lore.kernel.org/linux-rockchip/CANAwSgTTzZOwBaR9zjJ5VMpxm5BydtW6rB2S7jg+dnoX8hAoWg@mail.gmail.com/

The conclusions I draw from that rather ugly situation are:
 - The hwrng should not be enabled by default, but it should by done
   for each board on which it is known to work well.
 - RK_RNG_SAMPLE_CNT as well as the assumed rng quality should be
   defined in DT for each board:
   * introduce new 'rochchip,rng-sample-count' property
   * read 'quality' property already used for timeriomem_rng

I will prepare a follow-up patch taking those conclusions into account.

Just for completeness, here my test result on the NanoPi R5C:
root@OpenWrt:~# cat /dev/hwrng | rngtest -c 1000
rngtest 6.15
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

rngtest: starting FIPS tests...
rngtest: bits received from input: 20000032
rngtest: FIPS 140-2 successes: 875
rngtest: FIPS 140-2 failures: 125
rngtest: FIPS 140-2(2001-10-10) Monobit: 123
rngtest: FIPS 140-2(2001-10-10) Poker: 5
rngtest: FIPS 140-2(2001-10-10) Runs: 4
rngtest: FIPS 140-2(2001-10-10) Long run: 0
rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
rngtest: input channel speed: (min=85.171; avg=141.102; max=4882812.500)Kibits/s
rngtest: FIPS tests speed: (min=17.809; avg=19.494; max=60.169)Mibits/s
rngtest: Program run time: 139628605 microseconds