CPU clock frequency property in DTB

I have a question:

The following fragment from arch/arm64/kernel/topology.c prints an error for all CPU's on the HiKey.

rate = of_get_property(cn, "clock-frequency", &len); if (!rate || len != 4) { pr_err("%s: Missing clock-frequency property\n", cn->full_name); continue; }

This doesn't seem to be fatal, and Juno and other platforms do not seem to have it set. If that is the case, why is it an error, rather than a warning? Also if no one uses it why check for it at all? Backwards compatibility with other architectures?

Scott