Re: [PATCH v4 1/6] crypto: caam - RNG4 TRNG errata

[Horia Geanta]

On 11/25/2019 3:22 PM, Andrey Smirnov wrote:
> On Mon, Nov 25, 2019 at 12:02 AM Horia Geanta <horia.geanta@xxxxxxx> wrote:
>>
>> On 11/21/2019 5:56 PM, Andrey Smirnov wrote:
>>> The TRNG as used in RNG4, used in CAAM has a documentation issue. The
>> I assume the "erratum" consists in RTMCTL[TRNG_ACC] bit
>> not being documented, correct?
>>
>> Is there an ID of the erratum?
>> Or at least do you know what parts / SoCs have incorrect documentation?
>>
>>> effect is that it is possible that the entropy used to instantiate the
>>> DRBG may be old entropy, rather than newly generated entropy. There is
>>> proper programming guidance, but it is not in the documentation.
>>>
>> Is the "programming guidance" public?
>>
> 
> I don't know the answers to any of those questions. I am not the
> original author of this change, just ported if from NXP tree because
> it seemed important. More than happy to drop this if you think it's
> bogus.
> 
The implementation is fine.
I am just trying to understand the commit message.

Maybe Aymen, as author, could help.
Otherwise I suggest rewriting it, i.e. drop the mention of an erratum
and just say what's the problem in the RNG initialization code.

Thanks,
Horia