[PATCH] thermal: Use power efficient workqueue

[Leo Yan]

Thermal core framework uses the system_freezable_wq workqueue as its
workqueue for polling temperature. Using system_freezable_wq workqueue
prevents the scheduler to make smart decision about the best place to
schedule the work.

This commit replaces system_freezable_wq with
system_freezable_power_efficient_wq. With kernel configuration
CONFIG_WQ_POWER_EFFICIENT is enabled, the work can be scheduled on the
best CPU from a power or a performance point of view.

This commit is inspired by Vincent Guittot patch "netfilter: conntrack:
use power efficient workqueue" and verified on 96boards Hikey960.

Cc: Eduardo Valentin <edubezval@xxxxxxxxx>
Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
---
 drivers/thermal/thermal_core.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 2b1b0ba..ba90f71 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -293,11 +293,12 @@ static void thermal_zone_device_set_polling(struct thermal_zone_device *tz,
 					    int delay)
 {
 	if (delay > 1000)
-		mod_delayed_work(system_freezable_wq, &tz->poll_queue,
+		mod_delayed_work(system_freezable_power_efficient_wq,
+				 &tz->poll_queue,
 				 round_jiffies(msecs_to_jiffies(delay)));
 	else if (delay)
-		mod_delayed_work(system_freezable_wq, &tz->poll_queue,
-				 msecs_to_jiffies(delay));
+		mod_delayed_work(system_freezable_power_efficient_wq,
+				 &tz->poll_queue, msecs_to_jiffies(delay));
 	else
 		cancel_delayed_work(&tz->poll_queue);
 }
-- 
2.7.4