CPU frequency and RISC-V boards

Peter Kietzmann

Dear community,

how is the CPU frequency configured in zephyr? I found `clock-frequency`
configurations for `cpu0` in different device tree source files. This is
missing for hifive1_revb or rv32m1_vega_zero_riscy, however,
hifive1_revb defines `clock-frequency = <16000000>` (16 MHz) in multiple
peripheral structures. Is this the CPU frequency? The platform is
supposed to run with up to 320 MHz, though.

More specifically, I would like to run both platforms with maximum
speed. How can I achieve that? I'd be happy about any advice :).