Messages in this thread | | | Date | Tue, 29 Apr 2014 16:53:23 +0100 | From | Javi Merino <> | Subject | Re: [PATCH v2 3/4] thermal: Added Bang-bang thermal governor |
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On Tue, Apr 29, 2014 at 10:17:56AM +0100, 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.
I don't really understand why step-wise doesn't work for you (AIUI, this governor should be a subset of it. I'll let others comment on that, just a minor comment below.
[...] > diff --git a/drivers/thermal/gov_bang_bang.c b/drivers/thermal/gov_bang_bang.c > new file mode 100644 > index 0000000..328dde0 > --- /dev/null > +++ b/drivers/thermal/gov_bang_bang.c > @@ -0,0 +1,124 @@ > +/* > + * gov_bang_bang.c - A simple thermal throttling governor using hysteresis > + * > + * Copyright (C) 2014 Peter Feuerer <peter@piie.net> > + * > + * Based on step_wise.c with following Copyrights: > + * Copyright (C) 2012 Intel Corp > + * Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com> > + * > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation, version 2. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See > + * the GNU General Public License for more details. > + * > + */ > + > +#include <linux/thermal.h> > + > +#include "thermal_core.h" > + > +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 neither on nor off set the fan to active */ > + if (instance->target != 0 && instance->target != 1) > + instance->target = 1;
I think you should add a pr_warn() here to warn the user that the governor is being used with a cooling device that seems to support more than one cooling state.
Cheers, Javi
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