cpuidle: psci: Correct the domain-idlestate statistics in debugfs

When trying to enter a domain-idlestate, we may occasionally fail to enter
the state, which is informed to us by psci_cpu_suspend_enter() returning an
error-code. In these cases, our corresponding genpd->power_off() callback
has already returned zero to indicate success, leading to getting
in-correct domain-idlestate statistics in debugfs for the genpd in
question.

Let's fix this by making use of the new pm_genpd_inc_rejected() helper, as
it allows us to correct the domain-idlestate statistics for this type of
scenario.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20250314100103.1294715-4-ulf.hansson@linaro.org

Author: Ulf Hansson

drivers/cpuidle/cpuidle-psci-domain.c

@@ -43,7 +43,7 @@ static int psci_pd_power_off(struct generic_pm_domain *pd)
 
 	/* OSI mode is enabled, set the corresponding domain state. */
 	pd_state = state->data;
-	psci_set_domain_state(*pd_state);
+	psci_set_domain_state(pd, pd->state_idx, *pd_state);
 
 	return 0;
 }

drivers/cpuidle/cpuidle-psci.c

@@ -37,6 +37,8 @@ struct psci_cpuidle_data {
 };
 
 struct psci_cpuidle_domain_state {
+	struct generic_pm_domain *pd;
+	unsigned int state_idx;
 	u32 state;
 };
 
@@ -45,14 +47,14 @@ static DEFINE_PER_CPU(struct psci_cpuidle_domain_state, psci_domain_state);
 static bool psci_cpuidle_use_syscore;
 static bool psci_cpuidle_use_cpuhp;
 
-void psci_set_domain_state(u32 state)
+void psci_set_domain_state(struct generic_pm_domain *pd, unsigned int state_idx,
+			   u32 state)
 {
-	__this_cpu_write(psci_domain_state.state, state);
-}
+	struct psci_cpuidle_domain_state *ds = this_cpu_ptr(&psci_domain_state);
 
-static inline u32 psci_get_domain_state(void)
-{
-	return __this_cpu_read(psci_domain_state.state);
+	ds->pd = pd;
+	ds->state_idx = state_idx;
+	ds->state = state;
 }
 
 static inline void psci_clear_domain_state(void)
@@ -67,7 +69,8 @@ static __cpuidle int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
 	struct psci_cpuidle_data *data = this_cpu_ptr(&psci_cpuidle_data);
 	u32 *states = data->psci_states;
 	struct device *pd_dev = data->dev;
-	u32 state;
+	struct psci_cpuidle_domain_state *ds;
+	u32 state = states[idx];
 	int ret;
 
 	ret = cpu_pm_enter();
@@ -80,9 +83,9 @@ static __cpuidle int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
 	else
 		pm_runtime_put_sync_suspend(pd_dev);
 
-	state = psci_get_domain_state();
-	if (!state)
-		state = states[idx];
+	ds = this_cpu_ptr(&psci_domain_state);
+	if (ds->state)
+		state = ds->state;
 
 	trace_psci_domain_idle_enter(dev->cpu, state, s2idle);
 	ret = psci_cpu_suspend_enter(state) ? -1 : idx;
@@ -95,6 +98,10 @@ static __cpuidle int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
 
 	cpu_pm_exit();
 
+	/* Correct domain-idlestate statistics if we failed to enter. */
+	if (ret == -1 && ds->state)
+		pm_genpd_inc_rejected(ds->pd, ds->state_idx);
+
 	/* Clear the domain state to start fresh when back from idle. */
 	psci_clear_domain_state();
 	return ret;

drivers/cpuidle/cpuidle-psci.h

@@ -4,8 +4,10 @@
 #define __CPUIDLE_PSCI_H
 
 struct device_node;
+struct generic_pm_domain;
 
-void psci_set_domain_state(u32 state);
+void psci_set_domain_state(struct generic_pm_domain *pd, unsigned int state_idx,
+			   u32 state);
 int psci_dt_parse_state_node(struct device_node *np, u32 *state);
 
 #endif /* __CPUIDLE_PSCI_H */