[PATCH RFC 2/3] sched: idle: Add a latency parameter to the play_idle function

[Daniel Lezcano]

By default the play_idle() function leads to the deepest idle state
selection which is not necessarily the state we are interested in when
forcing the CPU to go to idle.

Add a latency parameter to the play_idle() function, so the caller can
use the constraint to allow a shallower state.

Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
---
 drivers/powercap/idle_inject.c           | 2 +-
 drivers/thermal/intel/intel_powerclamp.c | 2 +-
 include/linux/cpu.h                      | 2 +-
 kernel/sched/idle.c                      | 4 ++--
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c
index cd1270614cc6..6f2bfb172e61 100644
--- a/drivers/powercap/idle_inject.c
+++ b/drivers/powercap/idle_inject.c
@@ -138,7 +138,7 @@ static void idle_inject_fn(unsigned int cpu)
 	 */
 	iit->should_run = 0;
 
-	play_idle(READ_ONCE(ii_dev->idle_duration_us));
+	play_idle(READ_ONCE(ii_dev->idle_duration_us), UINT_MAX);
 }
 
 /**
diff --git a/drivers/thermal/intel/intel_powerclamp.c b/drivers/thermal/intel/intel_powerclamp.c
index 53216dcbe173..dd1330d59176 100644
--- a/drivers/thermal/intel/intel_powerclamp.c
+++ b/drivers/thermal/intel/intel_powerclamp.c
@@ -430,7 +430,7 @@ static void clamp_idle_injection_func(struct kthread_work *work)
 	if (should_skip)
 		goto balance;
 
-	play_idle(jiffies_to_usecs(w_data->duration_jiffies));
+	play_idle(jiffies_to_usecs(w_data->duration_jiffies), UINT_MAX);
 
 balance:
 	if (clamping && w_data->clamping && cpu_online(w_data->cpu))
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index d0633ebdaa9c..241f558af17a 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -179,7 +179,7 @@ void arch_cpu_idle_dead(void);
 int cpu_report_state(int cpu);
 int cpu_check_up_prepare(int cpu);
 void cpu_set_state_online(int cpu);
-void play_idle(unsigned long duration_us);
+void play_idle(unsigned long duration_us, unsigned int latency);
 
 #ifdef CONFIG_HOTPLUG_CPU
 bool cpu_wait_death(unsigned int cpu, int seconds);
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 00e064d3dfe1..56a8b9d35cb9 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -311,7 +311,7 @@ static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *timer)
 	return HRTIMER_NORESTART;
 }
 
-void play_idle(unsigned long duration_us)
+void play_idle(unsigned long duration_us, unsigned int latency)
 {
 	struct idle_timer it;
 
@@ -328,7 +328,7 @@ void play_idle(unsigned long duration_us)
 	rcu_sleep_check();
 	preempt_disable();
 	current->flags |= PF_IDLE;
-	cpuidle_use_latency(1);
+	cpuidle_use_latency(latency);
 
 	it.done = 0;
 	hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-- 
2.17.1