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thermal/core: Remove the 'forced_passive' option 

The code was reorganized in 2012 with the commit 0c01ebbfd3.

The main change is a loop on the trip points array and a unconditional
call to the throttle() ops of the governors for each of them even if
the trip temperature is not reached yet.

With this change, the 'forced_passive' is no longer checked in the
thermal_zone_device_update() function but in the step wise governor's
throttle() callback.

As the force_passive does no belong to the trip point array, the
thermal_zone_device_update() can not compare with the specified
passive temperature, thus does not detect the passive limit has been
crossed. Consequently, throttle() is never called and the
'forced_passive' branch is unreached.

In addition, the default processor cooling device is not automatically
bound to the thermal zone if there is not passive trip point, thus the
'forced_passive' can not operate.

If there is an active trip point, then the throttle function will be
called to mitigate at this temperature and the 'forced_passive' will
override the mitigation of the active trip point in this case but with
the default cooling device bound to the thermal zone, so usually a
fan, and that is not a passive cooling effect.

Given the regression exists since more than 8 years, nobody complained
and at the best of my knowledge there is no bug open in
https://bugzilla.kernel.org, it is reasonable to say it is unused.

Remove the 'forced_passive' related code.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Thara Gopinath <thara.gopinath@linaro.org>
Link: https://lore.kernel.org/r/20201214233811.485669-1-daniel.lezcano@linaro.org
This commit is contained in:
Daniel Lezcano 2020-12-15 00:38:04 +01:00
parent 04f111130e
commit a7d6ba14ef
4 changed files with 3 additions and 108 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
Documentation/driver-api/thermal/sysfs-api.rst
View File

@ -520,19 +520,6 @@ available_policies
RW, Optional
passive
Attribute is only present for zones in which the passive cooling
policy is not supported by native thermal driver. Default is zero
and can be set to a temperature (in millidegrees) to enable a
passive trip point for the zone. Activation is done by polling with
an interval of 1 second.
Unit: millidegrees Celsius
Valid values: 0 (disabled) or greater than 1000
RW, Optional
emul_temp
Interface to set the emulated temperature method in thermal zone
(sensor). After setting this temperature, the thermal zone may pass

14
drivers/thermal/gov_step_wise.c
View File

@ -109,7 +109,7 @@ static void update_passive_instance(struct thermal_zone_device *tz,
* If value is +1, activate a passive instance.
* If value is -1, deactivate a passive instance.
*/
if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
if (type == THERMAL_TRIP_PASSIVE)
tz->passive += value;
}
@ -122,13 +122,8 @@ static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
bool throttle = false;
int old_target;
if (trip == THERMAL_TRIPS_NONE) {
trip_temp = tz->forced_passive;
trip_type = THERMAL_TRIPS_NONE;
} else {
tz->ops->get_trip_temp(tz, trip, &trip_temp);
tz->ops->get_trip_type(tz, trip, &trip_type);
}
tz->ops->get_trip_temp(tz, trip, &trip_temp);
tz->ops->get_trip_type(tz, trip, &trip_type);
trend = get_tz_trend(tz, trip);
@ -189,9 +184,6 @@ static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
thermal_zone_trip_update(tz, trip);
if (tz->forced_passive)
thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
mutex_lock(&tz->lock);
list_for_each_entry(instance, &tz->thermal_instances, tz_node)

80
drivers/thermal/thermal_sysfs.c
View File

@ -216,49 +216,6 @@ trip_point_hyst_show(struct device *dev, struct device_attribute *attr,
return ret ? ret : sprintf(buf, "%d\n", temperature);
}
static ssize_t
passive_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct thermal_zone_device *tz = to_thermal_zone(dev);
int state;
if (sscanf(buf, "%d\n", &state) != 1)
return -EINVAL;
/* sanity check: values below 1000 millicelcius don't make sense
* and can cause the system to go into a thermal heart attack
*/
if (state && state < 1000)
return -EINVAL;
if (state && !tz->forced_passive) {
if (!tz->passive_delay)
tz->passive_delay = 1000;
thermal_zone_device_rebind_exception(tz, "Processor",
sizeof("Processor"));
} else if (!state && tz->forced_passive) {
tz->passive_delay = 0;
thermal_zone_device_unbind_exception(tz, "Processor",
sizeof("Processor"));
}
tz->forced_passive = state;
thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED);
return count;
}
static ssize_t
passive_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct thermal_zone_device *tz = to_thermal_zone(dev);
return sprintf(buf, "%d\n", tz->forced_passive);
}
static ssize_t
policy_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
@ -403,7 +360,6 @@ static DEVICE_ATTR_RW(sustainable_power);
/* These thermal zone device attributes are created based on conditions */
static DEVICE_ATTR_RW(mode);
static DEVICE_ATTR_RW(passive);
/* These attributes are unconditionally added to a thermal zone */
static struct attribute *thermal_zone_dev_attrs[] = {
@ -438,45 +394,9 @@ static const struct attribute_group thermal_zone_mode_attribute_group = {
.attrs = thermal_zone_mode_attrs,
};
/* We expose passive only if passive trips are present */
static struct attribute *thermal_zone_passive_attrs[] = {
&dev_attr_passive.attr,
NULL,
};
static umode_t thermal_zone_passive_is_visible(struct kobject *kobj,
struct attribute *attr,
int attrno)
{
struct device *dev = kobj_to_dev(kobj);
struct thermal_zone_device *tz;
enum thermal_trip_type trip_type;
int count, passive = 0;
tz = container_of(dev, struct thermal_zone_device, device);
for (count = 0; count < tz->trips && !passive; count++) {
tz->ops->get_trip_type(tz, count, &trip_type);
if (trip_type == THERMAL_TRIP_PASSIVE)
passive = 1;
}
if (!passive)
return attr->mode;
return 0;
}
static const struct attribute_group thermal_zone_passive_attribute_group = {
.attrs = thermal_zone_passive_attrs,
.is_visible = thermal_zone_passive_is_visible,
};
static const struct attribute_group *thermal_zone_attribute_groups[] = {
&thermal_zone_attribute_group,
&thermal_zone_mode_attribute_group,
&thermal_zone_passive_attribute_group,
/* This is not NULL terminated as we create the group dynamically */
};

4
include/linux/thermal.h
View File

@ -131,9 +131,6 @@ struct thermal_cooling_device {
trip point.
* @prev_high_trip: the above current temperature if you've crossed a
passive trip point.
* @forced_passive: If > 0, temperature at which to switch on all ACPI
* processor cooling devices. Currently only used by the
* step-wise governor.
* @need_update: if equals 1, thermal_zone_device_update needs to be invoked.
* @ops: operations this &thermal_zone_device supports
* @tzp: thermal zone parameters
@ -167,7 +164,6 @@ struct thermal_zone_device {
int passive;
int prev_low_trip;
int prev_high_trip;
unsigned int forced_passive;
atomic_t need_update;
struct thermal_zone_device_ops *ops;
struct thermal_zone_params *tzp;