On Thu, Jul 20, 2017 at 12:54 AM, Florian Fainelli <f.faine...@gmail.com> wrote: > Hi, > > We have a particular ARM CPU design that is drawing quite a lot of > current upon exit from WFI, and it does so in a way even before the > first instruction out of WFI is executed. That means we cannot influence > directly the exit from WFI other than by changing the state in which it > would be previously entered because of this "dead" time during which the > internal logic needs to ramp up back where it left. > > A naive approach to solving this problem because we have CPU frequency > scaling available would be to do the following: > > - just before entering WFI, switch to a low frequency OPP > - enter WFI > - upon exit from WFI, ramp up the frequency back to e.g: highest OPP > > Some of the parts that I am not exactly clear on would be: > > - would that qualify as a cpuidle governor of some kind that ties in > which cpufreq? > - would using cpufreq_driver_fast_switch() be an appropriate API to use > from outside
Generally, the idle driver is expected to manipulate OPPs as suitable for it at the low level. Thanks, Rafael