Re: HAB warning on imx6sx

[Rouven Czerwinski <r.czerwinski@pengutronix.de>]

On Tue, 2024-07-23 at 14:44 +0200, Stefano Manni wrote:
> Hi,
> 
> On Tue, 2024-07-23 at 14:24 +0200, Rouven Czerwinski wrote:
> > 
> > This is a common warning on some i.MX6 devices which indicates a
> > CAAM
> > RNG self-test failure, see the description in
> > drivers/crypto/caam/rng_self_test.c which should be run by the
> > bootloader to ensure that the RNG part of the CAAM is not faulty.
> > This requires the CAAM driver within barebox to be enabled.
> > 
> 
> after enabling CAAM I see:
> 
>   rng_self_test: RNG software self-test passed
>   caam 2100000.crypto@2100000.of: Instantiated RNG4 SH1
> 
> but the HAB warning is still there.
> 
> I read from drivers/crypto/caam/rng_self_test.c that the warning is
> a false positive due to an incorrect implementation of the RNG
> self-test procedure in the boot ROM.
> So running the RNG selftest in the bootloader shoul help find
> real RNG failures that may be obfuscated by this false positive.
> 
> Is correct my understanding?

Yes, this is correct. You'll probably want to send a patch to modify
the habv4_known_rng_fail_events[] array in drivers/hab/habv4.c, this
should prevent it from being displayed as an error. 

Best regards,
Rouven Czerwinski