On 7/19/2017 7:32 PM, Oleksij Rempel wrote: > On Wed, Jul 19, 2017 at 12:49:47PM +0000, Horia Geantă wrote: >> On 7/19/2017 10:45 AM, Oleksij Rempel wrote: >>> According documentation, it is NIST certified TRNG. >>> So, set high quality to let the HWRNG framework automatically use it. >>> >>> Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> >>> --- >>> drivers/crypto/caam/caamrng.c | 6 ++++++ >>> 1 file changed, 6 insertions(+) >>> >>> diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c >>> index 41398da3edf4..684c0bc88dfd 100644 >>> --- a/drivers/crypto/caam/caamrng.c >>> +++ b/drivers/crypto/caam/caamrng.c >>> @@ -292,10 +292,16 @@ static int caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev) >>> return 0; >>> } >>> >>> +/* >>> + * hwrng register struct >>> + * The trng is suppost to have 100% entropy, and thus >>> + * we register with a very high quality value. >>> + */ >>> static struct hwrng caam_rng = { >>> .name = "rng-caam", >>> .cleanup = caam_cleanup, >>> .read = caam_read, >>> + .quality = 999, >> >> Why not 1024, i.e. where is 999 coming from? > > It comes from s390-trng.c driver. > Should I use 1024 instead? > AFAICT the range for quality is from 0 to 1024 (no entropy -> perfect entropy). 1024 should be used since I'd expect a HW TRNG to provide perfect entropy unless otherwise stated. [Cc-ing Harald and Martin for awareness wrt. s390/trng.] Thanks, Horia