Borislav Petkov writes:
On Sat, May 03, 2014 at 07:59:23PM +0200, Peter Feuerer wrote:
The bang-bang thermal governor uses a hysteresis to switch abruptly on
or off a cooling device. It is intended to control fans, which can
not be throttled but just switched on or off.
Bang-bang cannot be set as default governor as it is intended for
special devices only. For those special devices the driver needs to
explicitely request it.
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Zhang Rui <rui.zh...@intel.com>
Cc: Andreas Mohr <a...@lisas.de>
Cc: Borislav Petkov <b...@suse.de>
Cc: Javi Merino <javi.mer...@arm.com>
Signed-off-by: Peter Feuerer <pe...@piie.net>
...
+static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
+{
+ long trip_temp;
+ unsigned long trip_hyst;
+ struct thermal_instance *instance;
+
+ tz->ops->get_trip_temp(tz, trip, &trip_temp);
+ tz->ops->get_trip_hyst(tz, trip, &trip_hyst);
+
+ dev_dbg(&tz->device, "Trip%d[temp=%ld]:temp=%d:hyst=%ld\n",
+ trip, trip_temp, tz->temperature,
+ trip_hyst);
+
+ mutex_lock(&tz->lock);
+
+ list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+ if (instance->trip != trip)
+ continue;
+
+ /* in case fan is in initial state, switch the fan off */
+ if (instance->target == THERMAL_NO_TARGET)
+ instance->target = 0;
+
+ /* in case fan is neither on nor off set the fan to active */
+ if (instance->target != 0 && instance->target != 1) {
->target is unsigned long so
if (instance->target > 1)
Right, but I wanted to clearly point out the two possible states.
(and btw, a whole unsigned long for a cooling state... 2^64-1 cooling
states, nice).
Hehe, true, maybe u8 makes more sense, so the compiler can take the action to
align it accordingly to prevent bit shifting.
+ pr_warn("Thermal instance %s controlled by bang-bang has
unexpected state: %ld\n",
+ instance->name, instance->target);
+ instance->target = 1;
+ }
Can that even happen?
It should not, but if so, we have a warning and I have the feeling we should
keep it there.
--
--peter;
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