Hi, Per discussion in [1] it seems that the kernel has no business managing this clock: once the SP clock is disabled, it's not sufficient to just enable it in order to bring the SP core back up. Just let the firmware keep it enabled and don't expose it to drivers. [1] https://lore.kernel.org/lkml/154783267051.169631.3197836544646625747@xxxxxxxxxxxxxxxxxxxxxxxxxx/ The "secure processor" (SP) core runs the keyboard firmware on the OLPC XO 1.75 laptop. Lubo