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@xxxxxxxxxx>
Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
Changes in v5:
- Make CPUHP function/variable initdata.
---
drivers/cpuidle/cpuidle-psci.c | 45 +++++++++++++++++++++++++++++++++-
include/linux/cpuhotplug.h | 1 +
2 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index 6e7804e697ed..9d779be27071 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -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:
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index e51ee772b9f5..01f04ed6ad92 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -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,
--
2.17.1
