cpuidle: play_idle: Increase the resolution to usec

The play_idle resolution is 1ms. The intel_powerclamp bases the idle
duration on jiffies. The idle injection API is also using msec based
duration but has no user yet.

Unfortunately, msec based time does not fit well when we want to
inject idle cycle precisely with shallow idle state.

In order to set the scene for the incoming idle injection user, move
the precision up to usec when calling play_idle.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

4 files changed, 7 insertions, 6 deletions

diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c
index 24ff2a068978..10601f4bdf72 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_ms));
+        play_idle(READ_ONCE(ii_dev->idle_duration_ms) * USEC_PER_MSEC);
 }
 
 /**
diff --git a/drivers/thermal/intel/intel_powerclamp.c b/drivers/thermal/intel/intel_powerclamp.c
index 5149a817456b..53216dcbe173 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_msecs(w_data->duration_jiffies));
+        play_idle(jiffies_to_usecs(w_data->duration_jiffies));
 
 balance:
         if (clamping && w_data->clamping && cpu_online(w_data->cpu))
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index fcb1386bb0d4..88dc0c653925 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_ms);
+void play_idle(unsigned long duration_us);
 
 #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 80940939b733..b98283fc6914 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_ms)
+void play_idle(unsigned long duration_us)
 {
         struct idle_timer it;
 
@@ -323,7 +323,7 @@ void play_idle(unsigned long duration_ms)
         WARN_ON_ONCE(current->nr_cpus_allowed != 1);
         WARN_ON_ONCE(!(current->flags & PF_KTHREAD));
         WARN_ON_ONCE(!(current->flags & PF_NO_SETAFFINITY));
-        WARN_ON_ONCE(!duration_ms);
+        WARN_ON_ONCE(!duration_us);
 
         rcu_sleep_check();
         preempt_disable();
@@ -333,7 +333,8 @@ void play_idle(unsigned long duration_ms)
         it.done = 0;
         hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
         it.timer.function = idle_inject_timer_fn;
-        hrtimer_start(&it.timer, ms_to_ktime(duration_ms), HRTIMER_MODE_REL_PINNED);
+        hrtimer_start(&it.timer, ns_to_ktime(duration_us * NSEC_PER_USEC),
+                      HRTIMER_MODE_REL_PINNED);
 
         while (!READ_ONCE(it.done))
                 do_idle();