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Commit 21bc42ab authored by Len Brown's avatar Len Brown
Browse files

ACPI: thermal: use round_jiffies when thermal zone polling is enabled 



Properly functioning systems do not use thermal zone polling,
they use event-based notification.

However, some users enable periodic thermal zone polling
to work around bugs on their platforms, and at least one
platform exists with a real _TZP that requests polling.

While thermal zone polling (_TZP) is specified in units to 0.1 seconds,
it actually has a maximum granularity of 1 second.  Thus, we can safely
round up the _TZP timeout to occur on the next 1-second boundary.
This will batch it with other 1-second-granularity timers in the
system and thus potentially extend processor idle duration.

Note that the same timer is used both for _TZP
and for passive processor thermal throttling.
We can not round up the timeout when it is used
for passive thermal throttling.

Also, we can not make this a deferrable timer,
as temperature is just as relevant during idle
as it is during non-idle.

Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 40ffbfad

drivers/acpi/thermal.c

+8 −5
Original line number Diff line number Diff line
@@ -711,6 +711,7 @@ static void acpi_thermal_check(void *data) 
	int result = 0;

	struct acpi_thermal *tz = data;

	unsigned long sleep_time = 0;

	unsigned long timeout_jiffies = 0;

	int i = 0;

	struct acpi_thermal_state state;
@@ -787,10 +788,13 @@ static void acpi_thermal_check(void *data) 
	 * a thermal event occurs).  Note that _TSP and _TZD values are

	 * given in 1/10th seconds (we must covert to milliseconds).

	 */

	if (tz->state.passive)

	if (tz->state.passive) {

		sleep_time = tz->trips.passive.tsp * 100;

	else if (tz->polling_frequency > 0)

		timeout_jiffies =  jiffies + (HZ * sleep_time) / 1000;

	} else if (tz->polling_frequency > 0) {

		sleep_time = tz->polling_frequency * 100;

		timeout_jiffies =  round_jiffies(jiffies + (HZ * sleep_time) / 1000);

	}



	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "%s: temperature[%lu] sleep[%lu]\n",

			  tz->name, tz->temperature, sleep_time));
@@ -804,12 +808,11 @@ static void acpi_thermal_check(void *data) 
			del_timer(&(tz->timer));

	} else {

		if (timer_pending(&(tz->timer)))

			mod_timer(&(tz->timer),

					jiffies + (HZ * sleep_time) / 1000);

			mod_timer(&(tz->timer), timeout_jiffies);

		else {

			tz->timer.data = (unsigned long)tz;

			tz->timer.function = acpi_thermal_run;

			tz->timer.expires = jiffies + (HZ * sleep_time) / 1000;

			tz->timer.expires = timeout_jiffies;

			add_timer(&(tz->timer));

		}

	}