Commit 9c6ceecb authored by Ulf Hansson's avatar Ulf Hansson
Browse files

cpuidle: psci: Support CPU hotplug for the hierarchical model 



When the hierarchical CPU topology is used and when a CPU is put offline,
that CPU prevents its PM domain from being powered off, which is because
genpd observes the corresponding attached device as being active from a
runtime PM point of view. Furthermore, any potential master PM domains are
also prevented from being powered off.

To address this limitation, let's add add a new CPU hotplug state
(CPUHP_AP_CPU_PM_STARTING) and register up/down callbacks for it, which
allows us to deal with runtime PM accordingly.

Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Reviewed-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Acked-by: default avatarRafael J. Wysocki <rafael@kernel.org>
parent ce85aef5

drivers/cpuidle/cpuidle-psci.c

+44 −1
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 


#define pr_fmt(fmt) "CPUidle PSCI: " fmt



#include <linux/cpuhotplug.h>

#include <linux/cpuidle.h>

#include <linux/cpumask.h>

#include <linux/cpu_pm.h>
@@ -31,6 +32,7 @@ struct psci_cpuidle_data { 


static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);

static DEFINE_PER_CPU(u32, domain_state);

static bool psci_cpuidle_use_cpuhp __initdata;



static inline void psci_set_domain_state(u32 state)

{
@@ -72,6 +74,44 @@ static int psci_enter_domain_idle_state(struct cpuidle_device *dev, 
	return ret;

}



static int psci_idle_cpuhp_up(unsigned int cpu)

{

	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);



	if (pd_dev)

		pm_runtime_get_sync(pd_dev);



	return 0;

}



static int psci_idle_cpuhp_down(unsigned int cpu)

{

	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);



	if (pd_dev) {

		pm_runtime_put_sync(pd_dev);

		/* Clear domain state to start fresh at next online. */

		psci_set_domain_state(0);

	}



	return 0;

}



static void __init psci_idle_init_cpuhp(void)

{

	int err;



	if (!psci_cpuidle_use_cpuhp)

		return;



	err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,

					"cpuidle/psci:online",

					psci_idle_cpuhp_up,

					psci_idle_cpuhp_down);

	if (err)

		pr_warn("Failed %d while setup cpuhp state\n", err);

}



static int psci_enter_idle_state(struct cpuidle_device *dev,

				struct cpuidle_driver *drv, int idx)

{
@@ -166,9 +206,11 @@ static int __init psci_dt_cpu_init_idle(struct cpuidle_driver *drv, 
		 * selection of a shared state for the domain, assumes the

		 * domain states are all deeper states.

		 */

		if (data->dev)

		if (data->dev) {

			drv->states[state_count - 1].enter =

				psci_enter_domain_idle_state;

			psci_cpuidle_use_cpuhp = true;

		}

	}



	/* Idle states parsed correctly, store them in the per-cpu struct. */
@@ -289,6 +331,7 @@ static int __init psci_idle_init(void) 
			goto out_fail;

	}



	psci_idle_init_cpuhp();

	return 0;



out_fail:

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -95,6 +95,7 @@ enum cpuhp_state { 
	CPUHP_AP_OFFLINE,

	CPUHP_AP_SCHED_STARTING,

	CPUHP_AP_RCUTREE_DYING,

	CPUHP_AP_CPU_PM_STARTING,

	CPUHP_AP_IRQ_GIC_STARTING,

	CPUHP_AP_IRQ_HIP04_STARTING,

	CPUHP_AP_IRQ_ARMADA_XP_STARTING,

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