Hi, On Sun, 23 Jun 2024 at 16:13, Aurelien Jarno <aurelien@xxxxxxxxxxx> wrote: > > Hi, > > On 2024-06-23 09:00, Krzysztof Kozlowski wrote: > > On 23/06/2024 05:33, Daniel Golle wrote: > > > + > > > + rk_rng->rng.name = dev_driver_string(dev); > > > +#ifndef CONFIG_PM > > > + rk_rng->rng.init = rk_rng_init; > > > + rk_rng->rng.cleanup = rk_rng_cleanup; > > > +#endif > > > + rk_rng->rng.read = rk_rng_read; > > > + rk_rng->rng.priv = (unsigned long) dev; > > > + rk_rng->rng.quality = 900; > > > > I doubt in this value. Usually SoC vendors do not provide datasheet with > > any reliable and verifiable (so one which could be proven by 3rd party) > > information. Can you provide a source? (and vendor downstream tree does > > not really count) > > As the original author of the patch, I am the one who have chosen the > value. I did it as explained in the commit message: > > | The TRNG device does not seem to have a signal conditionner and the FIPS > | 140-2 test returns a lot of failures. They can be reduced by increasing > | RK_RNG_SAMPLE_CNT, in a tradeoff between quality and speed. This value > | has been adjusted to get ~90% of successes and the quality value has > | been set accordingly. > > It is also explained, admittedly more briefly, above the > RK_RNG_SAMPLE_CNT #define, as the commit messages are not really > relevant anymore once the patches are accepted: > > | * TRNG collects osc ring output bit every RK_RNG_SAMPLE_CNT time. The value is > | * a tradeoff between speed and quality and has been adjusted to get a quality > | * of ~900 (~90% of FIPS 140-2 successes). > | */ > > The decision to adjust RK_RNG_SAMPLE_CNT to reach ~90% of FIPS 140-2 > successes was based on the quality chosen by most hw_random drivers > currently in the kernel sources. The FIPS 140-2 tests were performed > using rngtest from the rng-tools project. > > All that said, I am not an expert in that domain, so feel free to point > to the documentation or provide the correct method to determine the > quality. > > Regards > Aurelien > > [1] https://git.kernel.org/pub/scm/utils/kernel/rng-tools/rng-tools.git/ This is an old repository, the latest can be found below [1] https://github.com/nhorman/rng-tools However, I could not find the support from ARM and ARM64 in the repository below because all the assembly is written for the X86 arch. Thanks -Anand
