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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: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
This commit is contained in:
Ulf Hansson 2019-10-10 12:01:48 +02:00
parent ce85aef570
commit 9c6ceecb65
2 changed files with 45 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
drivers/cpuidle/cpuidle-psci.c
View File

@ -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:

1
include/linux/cpuhotplug.h
View File

@ -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,