[PATCH 2/2] cpuidle: psci: Enable s2idle when using OSI with the PM domain topology

[Ulf Hansson]

To select domain idle states for cpuidle-psci, the PM domains via genpd are
being managed by using runtime PM. This works fine for the regular idle
path, but it doesn't when doing s2idle.

More precisely, the domain idle states becomes temporarily disabled, which
is because the PM core disables runtime PM for devices during system
suspend. Even if genpd tries to power off the PM domain in the
suspend_noirq phase, that doesn't help to properly select a domain idle
state, as this needs to be done on per CPU basis.

Let's address the issue by enabling the syscore flag for the attached CPU
devices. This prevents genpd from trying to power off the corresponding PM
domains in the suspend_noirq phase. Moreover, let's assign a specific
->enter_s2idle() callback for the corresponding domain idle state and let
it invoke pm_genpd_syscore_poweroff|poweron(), rather than using runtime
PM.

Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
---
 drivers/cpuidle/cpuidle-psci-domain.c |  2 ++
 drivers/cpuidle/cpuidle-psci.c        | 30 +++++++++++++++++++++++----
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
index b6e9649ab0da..65437ba5fa78 100644
--- a/drivers/cpuidle/cpuidle-psci-domain.c
+++ b/drivers/cpuidle/cpuidle-psci-domain.c
@@ -324,6 +324,8 @@ struct device *psci_dt_attach_cpu(int cpu)
 	if (cpu_online(cpu))
 		pm_runtime_get_sync(dev);
 
+	dev_pm_syscore_device(dev, true);
+
 	return dev;
 }
 
diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index 74463841805f..6322d55a0a7d 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -19,6 +19,7 @@
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/psci.h>
+#include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/string.h>
@@ -52,8 +53,9 @@ static inline int psci_enter_state(int idx, u32 state)
 	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, idx, state);
 }
 
-static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
-					struct cpuidle_driver *drv, int idx)
+static int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
+					  struct cpuidle_driver *drv, int idx,
+					  bool s2idle)
 {
 	struct psci_cpuidle_data *data = this_cpu_ptr(&psci_cpuidle_data);
 	u32 *states = data->psci_states;
@@ -66,7 +68,10 @@ static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
 		return -1;
 
 	/* Do runtime PM to manage a hierarchical CPU toplogy. */
-	pm_runtime_put_sync_suspend(pd_dev);
+	if (s2idle)
+		pm_genpd_syscore_poweroff(pd_dev);
+	else
+		pm_runtime_put_sync_suspend(pd_dev);
 
 	state = psci_get_domain_state();
 	if (!state)
@@ -74,7 +79,10 @@ static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
 
 	ret = psci_cpu_suspend_enter(state) ? -1 : idx;
 
-	pm_runtime_get_sync(pd_dev);
+	if (s2idle)
+		pm_genpd_syscore_poweron(pd_dev);
+	else
+		pm_runtime_get_sync(pd_dev);
 
 	cpu_pm_exit();
 
@@ -83,6 +91,19 @@ static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
 	return ret;
 }
 
+static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
+					struct cpuidle_driver *drv, int idx)
+{
+	return __psci_enter_domain_idle_state(dev, drv, idx, false);
+}
+
+static int psci_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
+					       struct cpuidle_driver *drv,
+					       int idx)
+{
+	return __psci_enter_domain_idle_state(dev, drv, idx, true);
+}
+
 static int psci_idle_cpuhp_up(unsigned int cpu)
 {
 	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
@@ -170,6 +191,7 @@ static int psci_dt_cpu_init_topology(struct cpuidle_driver *drv,
 	 * deeper states.
 	 */
 	drv->states[state_count - 1].enter = psci_enter_domain_idle_state;
+	drv->states[state_count - 1].enter_s2idle = psci_enter_s2idle_domain_idle_state;
 	psci_cpuidle_use_cpuhp = true;
 
 	return 0;
-- 
2.25.1