in the librem5 branch we use a minimal workaround for cpuidle on top of mainline ATF. Until now we use a random state of the upstream master branch. Let's use the most recent "stable" tag which is v2.2 as our base.
@angus.ainslie this is trivial and I know we currently don't use it in the builder, but it would be nice to have and Ack from you anyway.