[PATCH RFC 13/27] ARM: cpuidle: Add runtime PM support for CPU idle

[Zhaoyang Huang]

On 18 November 2015 at 06:37, Lina Iyer <lina.iyer at linaro.org> wrote:
> Notify runtime PM when the CPU is going to be powered off in the idle
> state. This allows for runtime PM suspend/resume of the CPU as well as
> its PM domain.
>
> Cc: Daniel Lezcano <daniel.lezcano at linaro.org>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> Signed-off-by: Lina Iyer <lina.iyer at linaro.org>
> ---
>  drivers/cpuidle/cpuidle-arm.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
> index 545069d..8e72a23 100644
> --- a/drivers/cpuidle/cpuidle-arm.c
> +++ b/drivers/cpuidle/cpuidle-arm.c
> @@ -11,13 +11,16 @@
>
>  #define pr_fmt(fmt) "CPUidle arm: " fmt
>
> +#include <linux/cpu.h>
>  #include <linux/cpuidle.h>
>  #include <linux/cpumask.h>
>  #include <linux/cpu_pm.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/slab.h>
> +#include <linux/rcupdate.h>
>
>  #include <asm/cpuidle.h>
>
> @@ -45,6 +48,10 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
>
>         ret = cpu_pm_enter();
>         if (!ret) {
> +               struct device *cpu_dev = get_cpu_device(dev->cpu);
> +
> +               RCU_NONIDLE(pm_runtime_put_sync_suspend(cpu_dev));
By my test, it seems that the usage_count of cpu device will be
decrease to -1 and the code never runs here. If it need a runtime_put
somewhere?
> +
>                 /*
>                  * Pass idle state index to cpu_suspend which in turn will
>                  * call the CPU ops suspend protocol with idle index as a
> @@ -52,6 +59,7 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
>                  */
>                 arm_cpuidle_suspend(idx);
>
> +               RCU_NONIDLE(pm_runtime_get_sync(cpu_dev));
>                 cpu_pm_exit();
>         }
>
> --
> 2.1.4
>
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