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: Len Brown <len.brown@intel.com>

diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index bc6d5866ef9867452c2e2881d5e09df16824f094..15d5fdc66a96f708c7ebd5199ca2b5cc47efce56 100644 (file)
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -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));
                }
        }