On Monday 21 Sep 2020 at 13:20:04 (+0100), Lukasz Luba wrote: > Devfreq cooling needs to now the correct status of the device in order > to operate. Do not rely on Devfreq last_status which might be a stale data > and get more up-to-date values of the load. > > Devfreq framework can change the device status in the background. To > mitigate this situation make a copy of the status structure and use it > for internal calculations. > > In addition this patch adds normalization function, which also makes sure > that whatever data comes from the device, it is in a sane range. > > Signed-off-by: Lukasz Luba <lukasz.l...@arm.com> > --- > drivers/thermal/devfreq_cooling.c | 52 +++++++++++++++++++++++++------ > 1 file changed, 43 insertions(+), 9 deletions(-) > > diff --git a/drivers/thermal/devfreq_cooling.c > b/drivers/thermal/devfreq_cooling.c > index 7063ccb7b86d..cf045bd4d16b 100644 > --- a/drivers/thermal/devfreq_cooling.c > +++ b/drivers/thermal/devfreq_cooling.c > @@ -227,6 +227,24 @@ static inline unsigned long get_total_power(struct > devfreq_cooling_device *dfc, > voltage); > } > > +static void _normalize_load(struct devfreq_dev_status *status)
Is there a reason for the leading "_" ? AFAIK, "__name()" is meant to suggest a "worker" function for another "name()" function, but that would not apply here. > +{ > + /* Make some space if needed */ > + if (status->busy_time > 0xffff) { > + status->busy_time >>= 10; > + status->total_time >>= 10; > + } How about removing the above code and adding here: status->busy_time = status->busy_time ? : 1; > + > + if (status->busy_time > status->total_time) This check would then cover the possibility that total_time is 0. > + status->busy_time = status->total_time; But a reversal is needed here: status->total_time = status->busy_time; > + > + status->busy_time *= 100; > + status->busy_time /= status->total_time ? : 1; > + > + /* Avoid division by 0 */ > + status->busy_time = status->busy_time ? : 1; > + status->total_time = 100; Then all of this code can be replaced by: status->busy_time = (unsigned long)div64_u64((u64)status->busy_time << 10, status->total_time); status->total_time = 1 << 10; This way you gain some resolution to busy_time and the divisions in the callers would just become shifts by 10. Hope it helps, Ionela.