Messages in this thread | | | Date | Thu, 3 Jun 2021 08:07:39 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH 2/3] PM: domains: Drop/restore performance state votes for devices at runtime PM |
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On 03-06-21, 08:04, Viresh Kumar wrote: > On 02-06-21, 12:12, Ulf Hansson wrote: > > A subsystem/driver that need to manage OPPs for its device, should > > typically drop its vote for the OPP when the device becomes runtime > > suspended. In this way, the corresponding aggregation of the performance > > state votes that is managed in genpd for the attached PM domain, may find > > that the aggregated vote can be decreased. Hence, it may allow genpd to set > > the lower performance state for the PM domain, thus avoiding to waste > > energy. > > > > To accomplish this, typically a subsystem/driver would need to call > > dev_pm_opp_set_rate|opp() for its device from its ->runtime_suspend() > > callback, to drop the vote for the OPP. Accordingly, it needs another call > > to dev_pm_opp_set_rate|opp() to restore the vote for the OPP from its > > ->runtime_resume() callback. > > > > To avoid boilerplate code in subsystems/driver to deal with these things, > > let's instead manage this internally in genpd. > > > > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> > > --- > > drivers/base/power/domain.c | 21 +++++++++++++++++++-- > > include/linux/pm_domain.h | 1 + > > 2 files changed, 20 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > > index a3b6e751f366..81b9d4652b90 100644 > > --- a/drivers/base/power/domain.c > > +++ b/drivers/base/power/domain.c > > @@ -397,6 +397,18 @@ static int genpd_set_performance_state(struct device *dev, unsigned int state) > > return ret; > > } > > > > +static int genpd_drop_performance_state(struct device *dev) > > +{ > > + struct generic_pm_domain_data *gpd_data = dev_gpd_data(dev); > > + unsigned int prev_state; > > + > > + prev_state = gpd_data->performance_state; > > + if (prev_state && !genpd_set_performance_state(dev, 0)) > > What about adding this prev_state check in > genpd_set_performance_state() itself ? We already have one for the > genpd in _genpd_set_performance_state(), why not one for the device ? > > > + return prev_state; > > + > > + return 0; > > Hmm, we will return 0 in case genpd_set_performance_state() fails, > which will make us set the state to 0 again on resume. Maybe add a > comment for this somewhere ?
No, we won't as you check for rpm_saved_pstate there, so the device will stay disabled.
Again adding the check into genpd_set_performance_state() may help reducing similar checks elsewhere.
> > +} > > + > > /** > > * dev_pm_genpd_set_performance_state- Set performance state of device's power > > * domain. > > @@ -839,7 +851,8 @@ static int genpd_runtime_suspend(struct device *dev) > > { > > struct generic_pm_domain *genpd; > > bool (*suspend_ok)(struct device *__dev); > > - struct gpd_timing_data *td = &dev_gpd_data(dev)->td; > > + struct generic_pm_domain_data *gpd_data = dev_gpd_data(dev); > > + struct gpd_timing_data *td = &gpd_data->td; > > bool runtime_pm = pm_runtime_enabled(dev); > > ktime_t time_start; > > s64 elapsed_ns; > > @@ -896,6 +909,7 @@ static int genpd_runtime_suspend(struct device *dev) > > return 0; > > > > genpd_lock(genpd); > > + gpd_data->rpm_saved_pstate = genpd_drop_performance_state(dev); > > genpd_power_off(genpd, true, 0); > > genpd_unlock(genpd); > > > > @@ -913,7 +927,8 @@ static int genpd_runtime_suspend(struct device *dev) > > static int genpd_runtime_resume(struct device *dev) > > { > > struct generic_pm_domain *genpd; > > - struct gpd_timing_data *td = &dev_gpd_data(dev)->td; > > + struct generic_pm_domain_data *gpd_data = dev_gpd_data(dev); > > + struct gpd_timing_data *td = &gpd_data->td; > > bool runtime_pm = pm_runtime_enabled(dev); > > ktime_t time_start; > > s64 elapsed_ns; > > @@ -937,6 +952,8 @@ static int genpd_runtime_resume(struct device *dev) > > > > genpd_lock(genpd); > > ret = genpd_power_on(genpd, 0); > > + if (!ret && gpd_data->rpm_saved_pstate) > > + genpd_set_performance_state(dev, gpd_data->rpm_saved_pstate); > > genpd_unlock(genpd);
-- viresh
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