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

[Lina Iyer <lina.iyer@linaro.org>]

On Wed, Nov 11 2015 at 02:10 -0700, Zhaoyang Huang wrote:
>On 6 October 2015 at 22:27, Marc Titinger <mtitinger@baylibre.com> wrote:
>> From: Marc Titinger <mtitinger@baylibre.com>
>>
>> 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@baylibre.com>
>> ---
>>  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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