Skip to content

Draft: hack: crypto: caam - fix i.MX8MQ entropy delay value

Martin Kepplinger requested to merge martin.kepplinger/linux-next:entropy_delay into pureos/byzantium

Similar to commit 4ee4cdad ("crypto: caam - fix i.MX6SX entropy delay value") increase the delay (nr of system clock cycles) the RNG has to get 1 bit of entropy.

With the default value (3200) we see errors like: caam_jr 30902000.jr: 2000025b: CCB: desc idx 2: RNG: Hardware error

Vabhav wanted to adda DT property even, to make this more configurable: https://lore.kernel.org/linux-arm-kernel/20220530180924.1792399-1-vabhav.sharma@nxp.com/ which just would need finding a suitible format / physical unit. But in case the value from imx6sx is appropriate for imx8mq too, let's keep this oneliner.

Probably Fixes #467 (closed)

3200 (clock cycles) is the default - apprearently too low. this uses 12000. Since NXP ran some tests and the imx6sx RNG is at least compatible with the imx8mq one (not sure if exactly the same), I'd suggest to use 12000. But we could as well test whether a lower value would be enough - but then again - how would we really know?

Edited by Martin Kepplinger

Merge request reports