Hello,

The FIH functionality reference implementation on AN521 was there before, and then get turned off last year because it increases the effort of updating the HAL interface.

Now the HAL interface update is done, this functionality is re-enabled on AN521, based on the updated HAL. The patches are pushed for your review: https://review.trustedfirmware.org/q/topic:%22FIH_AN521_RE%22+(status:open%2...)

The mechanism is mainly the same as the previous implementation, The document is under modifying to reflect the re-enablement changes but still can be read to recall the general concept: https://tf-m-user-guide.trustedfirmware.org/technical_references/design_docs...

Please leave your comments in the patches or do overall discussions in this mail thread.

Thanks!

/Ken