On Wed, Oct 27, 2021 at 02:02:33PM +0200, AngeloGioacchino Del Regno wrote:
> To allow this device to fill the kernel's entropy pool at boot,
> setup a default quality for the hwrng found in Cr50.
>
> After some testing with rngtest and dieharder it was, in short,
> discovered that the RNG produces fair quality randomness, giving
> around 99.93% successes in rngtest FIPS140-2.
>
> Notably, though, when testing with dieharder it was noticed that
> the p-values distribution wasn't uniform in all the cases, so a
> conservative quality value was chosen.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> ---
> drivers/char/tpm/tpm_tis_spi_cr50.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/char/tpm/tpm_tis_spi_cr50.c b/drivers/char/tpm/tpm_tis_spi_cr50.c
> index ea759af25634..d6195fb58036 100644
> --- a/drivers/char/tpm/tpm_tis_spi_cr50.c
> +++ b/drivers/char/tpm/tpm_tis_spi_cr50.c
> @@ -264,6 +264,7 @@ int cr50_spi_probe(struct spi_device *spi)
> phy = &cr50_phy->spi_phy;
> phy->flow_control = cr50_spi_flow_control;
> phy->wake_after = jiffies;
> + phy->priv.rng_quality = 700;
How did you end up exactly to this number ('700')?
/Jarkko
