Re: [RFC v2 5/6] arm: cpuidle: let genpd handle the cluster power transition with 'power-states'

[Lina Iyer]

On Wed, Nov 11 2015 at 02:10 -0700, Zhaoyang Huang wrote:
> On 6 October 2015 at 22:27, Marc Titinger <mtitinger@xxxxxxxxxxxx> wrote:
> > From: Marc Titinger <mtitinger@xxxxxxxxxxxx>
> >
> > Cpuidle now handles c-states and power-states differently. c-states do not decrement
> >  the reference count for the CPUs in the cluster, while power-states i.e.
> > cluster level states like 'CLUSTER_SLEEP_0' in the case of juno, will.
> >
> > The 'D1' fake device also registers intermediate power-state,
> > for experimentation.
> >
> > Signed-off-by: Marc Titinger <mtitinger@xxxxxxxxxxxx>
> > ---
> >  arch/arm64/boot/dts/arm/juno.dts |  2 +-
> >  drivers/cpuidle/cpuidle-arm.c    | 52 ++++++++++++++++++++++++++++++++--------
> >  2 files changed, 43 insertions(+), 11 deletions(-)
> >
> > diff --git a/arch/arm64/boot/dts/arm/juno.dts b/arch/arm64/boot/dts/arm/juno.dts
> > index cadc5de..0bb0dd7 100644
> > --- a/arch/arm64/boot/dts/arm/juno.dts
> > +++ b/arch/arm64/boot/dts/arm/juno.dts
> > @@ -47,7 +47,7 @@
> >                         };
> >
> >                         CLUSTER_SLEEP_0: cluster-sleep-0 {
> > -                               compatible = "arm,idle-state","arm,power-state";
> > +                               compatible = "arm,power-state";
> >                                 arm,psci-suspend-param = <0x1010000>;
> >                                 local-timer-stop;
> >                                 entry-latency-us = <800>;
> > diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
> > index 7c791f9..8dd5dc3 100644
> > --- a/drivers/cpuidle/cpuidle-arm.c
> > +++ b/drivers/cpuidle/cpuidle-arm.c
> > @@ -40,7 +40,6 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
> >                                 struct cpuidle_driver *drv, int idx)
> >  {
> >         int ret;
> > -       struct device *cpu_dev = get_cpu_device(dev->cpu);
> >
> >         if (!idx) {
> >                 cpu_do_idle();
> > @@ -50,18 +49,49 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
> >         ret = cpu_pm_enter();
> >         if (!ret) {
> >                 /*
> > -                * Notify runtime PM as well of this cpu powering down
> > -                * TODO: Merge CPU_PM and runtime PM.
> > -                */
> > -               RCU_NONIDLE(pm_runtime_put_sync(cpu_dev));
> > -
> > -               /*
> >                  * Pass idle state index to cpu_suspend which in turn will
> >                  * call the CPU ops suspend protocol with idle index as a
> >                  * parameter.
> >                  */
> >                 arm_cpuidle_suspend(idx);
> >
> > +               cpu_pm_exit();
> > +       }
> > +
> > +       return ret ? -1 : idx;
> > +}
> > +
> > +/*
> > + * arm_enter_power_state - delegate state trasition to genpd
> > + *
> > + * dev: cpuidle device
> > + * drv: cpuidle driver
> > + * idx: state index
> > + *
> > + * Called from the CPUidle framework to delegate a state transition
> > + * to the generic domain. This will be a cluster poweroff state
> > + * the Domain will chose to actually turn off the cluster based on
> > + * the status of other CPUs, and devices and subdomains in the Cluster
> > + * domain.
> > +*/
> > +static int arm_enter_power_state(struct cpuidle_device *dev,
> > +               struct cpuidle_driver *drv, int idx)
> > +{
> > +       int ret;
> > +       struct device *cpu_dev = get_cpu_device(dev->cpu);
> > +
> > +       BUG_ON(idx == 0);
> > +
> > +       ret = cpu_pm_enter();
> > +       if (!ret) {
> > +               /*
> > +               * Notify runtime PM as well of this cpu powering down
> > +               * TODO: Merge CPU_PM and runtime PM.
> > +               */
> > +               RCU_NONIDLE(pm_runtime_put_sync(cpu_dev));
> [question]: Does it mean that above function will use the gpd->rpm->idle?

Will end up at rpm_suspend() in runtime.c which will callinto genpd. Its
not a direct call to genpd.

Thanks,
Lina

> > +
> > +               arm_cpuidle_suspend(idx);
> > +
> >                 RCU_NONIDLE(pm_runtime_get_sync(cpu_dev));
> >                 cpu_pm_exit();
> >         }
> > @@ -69,6 +99,7 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
> >         return ret ? -1 : idx;
> >  }
> >
> > +
> >  static struct cpuidle_driver arm_idle_driver = {
> >         .name = "arm_idle",
> >         .owner = THIS_MODULE,
> > @@ -90,9 +121,10 @@ static struct cpuidle_driver arm_idle_driver = {
> >  };
> >
> >  static const struct of_device_id arm_idle_state_match[] __initconst = {
> > -       { .compatible = "arm,idle-state",
> > -         .data = arm_enter_idle_state },
> > -       { },
> > +       {.compatible = "arm,idle-state",
> > +        .data = arm_enter_idle_state},
> > +       {.compatible = "arm,power-state",
> > +        .data = arm_enter_power_state},
> >  };
> >
> >  /*
> > --
> > 1.9.1
> >
> > --
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