On Mon, 2022-04-25 at 15:30 +0530, Viresh Kumar wrote: > On 25-04-22, 17:34, Rex-BC Chen wrote: > > We found that the pulses of cpu voltage could be observed when > > frequency is fixed (scaling_max_freq == scaling_min_freq) if using > > cpufreq_generic_get as '.get' callback in MT8186. > > cpufreq framework will constantly (~ 1 sec) call 'update' if the > > policy > > Which function gets called here in that case ? I would expect > cpufreq_driver_target() to not make a call to MTK driver in that > case, after it > finds that new and old frequency are same (it will check the > corresponding freq > from cpufreq table). > > > frequency is NOT equal to hardware frequency in > > cpufreq_verify_current_freq. > > The problem is that there might be a tiny difference between the > > policy > > frequency and the hardware frequency even they are very close. > > e.g. policy frequency is 500,000,000 Hz however, hardware frequency > > is > > 499,999,726 Hz for MT8186 opp15. > > > > To prevent the voltage pulses, we currently use the software cached > > values as you pointed out. > > I wonder is it possible to add a tolerence for checking difference > > between policy frequency and hardware frequency in cpufreq > > framework so > > that we can use cpufreq_generic_get as callback without pulse > > issue. > > Or any suggestion would be appreciated. > > Hello Viresh, We have a non-upstream driver which tries to get frequency by 'cpufreq_get'. When we use that non-upstream driver, 'cpufreq_verify_current_freq' will be further invoked by 'cpufreq_get' and it would cause voltage pulse issue as I described previously. Therefore, we apply the solution in this series. Recently, we found that using 'cpufreq_generic_get' directly in our non-upstream driver can do the same thing without pulse issue. It can meet your request as well. So here, for cpufreq, I think it is proper to drop this patch and I will do it in the next version. Thanks for your review. BRs, Rex
