caam: Possible caam-rng regression since enabling prediction resistance

[Clemens Gruber <clemens.gruber@xxxxxxxxxxxx>]

Hi,

I noticed that /dev/hwrng blocks indefinitely on our i.MX6Q (rev1.6)
boards in recent kernel versions.
As it did work before, I ran git bisect and found that reverting the
following commit fixes the issue:
358ba762d9f1 ("crypto: caam - enable prediction resistance in HRWNG")

cat /dev/hwrng | rngtest looks good on Linux 5.15 with aforementioned
commit reverted.
U-Boot version is 2021.07 and the RNG is not instantiated there.

Any ideas what the problem could be with that commit and did you test
the changes on i.MX6 devices?

Let me know if you need more information / debug output / etc.

Best regards,
Clemens