> -----Original Message-----
> From: Peng Fan (OSS) <[email protected]>
> Sent: Tuesday, September 23, 2025 2:43 PM
> To: Gaurav Jain <[email protected]>
> Cc: Horia Geanta <[email protected]>; Pankaj Gupta
> <[email protected]>; Varun Sethi <[email protected]>; Silvano Di Ninno
> <[email protected]>; Meenakshi Aggarwal
> <[email protected]>; Tom Rini <[email protected]>; Fabio
> Estevam <[email protected]>; Peng Fan <[email protected]>; Simon Glass
> <[email protected]>; Baehring, Olaf <[email protected]>; Heinrich
> Schuchardt <[email protected]>; [email protected]
> Subject: Re: [PATCH] crypto/rng: double the entropy delay interval for retry
>
> Hi Gaurav,
>
> On Fri, Sep 05, 2025 at 03:03:48PM +0530, Gaurav Jain wrote:
> >during entropy evaluation, if the generated samples fail any
> >statistical test, then, all of the bits will be discarded, and a second
> >set of samples will be generated and tested.
> >
> >the entropy delay interval should be doubled before performing retry.
> >
> >Signed-off-by: Gaurav Jain <[email protected]>
> >---
> > drivers/crypto/fsl/jr.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >diff --git a/drivers/crypto/fsl/jr.c b/drivers/crypto/fsl/jr.c index
> >8f7a821ebf3..07d336c074a 100644
> >--- a/drivers/crypto/fsl/jr.c
> >+++ b/drivers/crypto/fsl/jr.c
> >@@ -642,7 +642,7 @@ static int rng_init(uint8_t sec_idx, ccsr_sec_t *sec)
> > */
> > if (!inst_handles) {
> > kick_trng(ent_delay, sec);
> >- ent_delay += 400;
> >+ ent_delay = ent_delay * 2;
>
> I not get the point on why need to double, would you please update the commit
> why not 500, 800 or else. What make ent_delay * 2 the best choice?
The typical reason a re-try is required when the entropy delay value is set too
low.
Therefore, when the re-try is attempted the entropy delay is doubled, thus
giving twice as long to generate each bit of entropy.
This is done to prevent having too many failures.
Regards
Gaurav Jain
>
> Thanks,
> Peng
>
> > }
> > /*
> > * if instantiate_rng(...) fails, the loop will rerun
> >--
> >2.25.1
> >
