linux-kernel - [PATCH V2 2/2] cpuidle: Use the latency to call find_deepest_idle

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Message-Id: <20191116131613.15733-2-daniel.lezcano@linaro.org>
Date:   Sat, 16 Nov 2019 14:16:13 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     rafael@...nel.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        ulf.hansson@...aro.org
Subject: [PATCH V2 2/2] cpuidle: Use the latency to call find_deepest_idle_state

As the dev->forced_idle_latency_limit_ns is filled with the latency
value when this function is called, use it as a parameter to the
find_deepest_idle_state() function.

Suggested-by: Rafael J. Wysocki <rafael@...nel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
---
 drivers/cpuidle/cpuidle.c | 7 +++++--
 include/linux/cpuidle.h   | 6 ++++--
 kernel/sched/idle.c       | 8 +++++++-
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 62226fadc02d..a02b701fc289 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -122,9 +122,12 @@ void cpuidle_use_deepest_state(u64 latency_limit_ns)
  * @dev: cpuidle device for the given CPU.
  */
 int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
-			       struct cpuidle_device *dev)
+			       struct cpuidle_device *dev,
+			       u64 latency_limit_ns)
 {
-	return find_deepest_state(drv, dev, UINT_MAX, 0, false);
+	return find_deepest_state(drv, dev,
+				  div_u64(latency_limit_ns, NSEC_PER_USEC),
+				  0, false);
 }
 
 #ifdef CONFIG_SUSPEND
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 1f3f4dd01e48..b60f35b7d53e 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -207,13 +207,15 @@ static inline struct cpuidle_device *cpuidle_get_device(void) {return NULL; }
 
 #ifdef CONFIG_CPU_IDLE
 extern int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
-				      struct cpuidle_device *dev);
+				      struct cpuidle_device *dev,
+				      u64 latency_limit_ns);
 extern int cpuidle_enter_s2idle(struct cpuidle_driver *drv,
 				struct cpuidle_device *dev);
 extern void cpuidle_use_deepest_state(u64 latency_limit_ns);
 #else
 static inline int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
-					     struct cpuidle_device *dev)
+					     struct cpuidle_device *dev,
+					     u64 latency_limit_ns)
 {return -ENODEV; }
 static inline int cpuidle_enter_s2idle(struct cpuidle_driver *drv,
 				       struct cpuidle_device *dev)
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 0a817e907192..fd4a8747e602 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -166,6 +166,9 @@ static void cpuidle_idle_call(void)
 	 */
 
 	if (idle_should_enter_s2idle() || dev->forced_idle_latency_limit_ns) {
+
+		u64 latency_limit_ns = dev->forced_idle_latency_limit_ns;
+
 		if (idle_should_enter_s2idle()) {
 			rcu_idle_enter();
 
@@ -176,12 +179,15 @@ static void cpuidle_idle_call(void)
 			}
 
 			rcu_idle_exit();
+
+			latency_limit_ns = U64_MAX;
 		}
 
 		tick_nohz_idle_stop_tick();
 		rcu_idle_enter();
 
-		next_state = cpuidle_find_deepest_state(drv, dev);
+		next_state = cpuidle_find_deepest_state(drv, dev,
+							latency_limit_ns);
 		call_cpuidle(drv, dev, next_state);
 	} else {
 		bool stop_tick = true;
-- 
2.17.1