Re: [PATCH v5 1/5] thermal: Add support for hardware-tracked trip points

Eduardo Valentin
2016-07-02T01:39:21Z

On Wed, Jun 22, 2016 at 11:15:19AM +0800, Zhang Rui wrote:
> On 一, 2016-06-06 at 19:44 +0800, Caesar Wang wrote:
> > From: Sascha Hauer <s.hauer@pengutronix.de>
> >
> > This adds support for hardware-tracked trip points to the device tree
> > thermal sensor framework.
> >
> > The framework supports an arbitrary number of trip points. Whenever
> > the current temperature is updated, the trip points immediately
> > below and above the current temperature are found. A .set_trips
> > callback is then called with the temperatures. If there is no trip
> > point above or below the current temperature, the passed trip
> > temperature will be -INT_MAX or INT_MAX respectively. In this
> > callback,
> > the driver should program the hardware such that it is notified
> > when either of these trip points are triggered. When a trip point
> > is triggered, the driver should call `thermal_zone_device_update'
> > for the respective thermal zone. This will cause the trip points
> > to be updated again.
> >
> > If .set_trips is not implemented, the framework behaves as before.
> >
> > This patch is based on an earlier version from Mikko Perttunen
> > <mikko.perttunen@kapsi.fi>
> >
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > Signed-off-by: Caesar Wang <wxt@rock-chips.com>
> > Cc: Zhang Rui <rui.zhang@intel.com>
> > Cc: Eduardo Valentin <edubezval@gmail.com>
> > Cc: linux-pm@vger.kernel.org
> >
> > ---
> >
> > Changes in v5:
> > - add the lock for thermal_zone_set_trips function.
> > - change based on next kernel.
> >
> > Changes in v4:
> > - Missing the lock added in v3.
> >
> > Changes in v3:
> > - as Javi comments on https://patchwork.kernel.org/patch/9001281/.
> > - add the lock for preventing the called from multi placce
> > - add the note for pre_low/high_trip.
> >
> > Changes in v2:
> > - update the sysfs-api.txt for set_trips.
> >
> >  Documentation/thermal/sysfs-api.txt |  7 +++++
> >  drivers/thermal/thermal_core.c      | 54
> > +++++++++++++++++++++++++++++++++++++
> >  drivers/thermal/thermal_sysfs.c     |  3 +++
> >  include/linux/thermal.h             | 10 +++++++
> >  4 files changed, 74 insertions(+)
> >
> > diff --git a/Documentation/thermal/sysfs-api.txt
> > b/Documentation/thermal/sysfs-api.txt
> > index efc3f3d..75d8838 100644
> > --- a/Documentation/thermal/sysfs-api.txt
> > +++ b/Documentation/thermal/sysfs-api.txt
> > @@ -49,6 +49,9 @@ temperature) and throttle appropriate devices.
> >   .bind: bind the thermal zone device with a thermal cooling
> > device.
> >   .unbind: unbind the thermal zone device with a thermal
> > cooling device.
> >   .get_temp: get the current temperature of the thermal zone.
> > + .set_trips: set the trip points window. Whenever the current
> > temperature
> > +     is updated, the trip points immediately below
> > and above the
> > +     current temperature are found.
> >   .get_mode: get the current mode (enabled/disabled) of the
> > thermal zone.
> >       - "enabled" means the kernel thermal management is
> > enabled.
> >       - "disabled" will prevent kernel thermal driver action
> > upon trip points
> > @@ -95,6 +98,10 @@ temperature) and throttle appropriate devices.
> >   get_temp: a pointer to a function
> > that reads the
> >   sensor temperature. This is
> > mandatory
> >   callback provided by sensor
> > driver.
> > + set_trips:      a pointer to a function that
> > sets a
> > + temperature window. When
> > this window is
> > + left the driver must inform
> > the thermal
> > + core via
> > thermal_zone_device_update.
> >   get_trend:  a pointer to a function
> > that reads the
> >   sensor temperature trend.
> >   set_emul_temp: a pointer to a
> > function that sets
> > diff --git a/drivers/thermal/thermal_core.c
> > b/drivers/thermal/thermal_core.c
> > index 792aab7..e69aee2 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -368,6 +368,56 @@ static void handle_thermal_trip(struct
> > thermal_zone_device *tz, int trip)
> >   monitor_thermal_zone(tz);
> >  }
> >
> > +void thermal_zone_set_trips(struct thermal_zone_device *tz)
> > +{
> > + int low = -INT_MAX;
> > + int high = INT_MAX;
> > + int trip_temp, hysteresis;
> > + int i, ret;
> > +
> > + mutex_lock(&tz->lock);
> > +
> > + if (!tz->ops->set_trips)
> > + goto exit;
> > +
> if (!tz->ops->get_trip_hyst)
> goto exit;
>
> otherwise, the patch looks good to me.

Agreed here, you need to check if get_trip_hyst is present before
calling it. Not all drivers have it.

Besides, I would prefer you to lock after the checks:

if (!tz->ops->set_trips)
return;

if (!tz->ops->get_trip_hyst)
return;

mutex_lock(&tz->lock);

>
> thanks,
> rui
> > + for (i = 0; i < tz->trips; i++) {
> > + int trip_low;
> > +
> > + tz->ops->get_trip_temp(tz, i, &trip_temp);
> > + tz->ops->get_trip_hyst(tz, i, &hysteresis);
> > +
> > + trip_low = trip_temp - hysteresis;
> > +
> > + if (trip_low < tz->temperature && trip_low > low)
> > + low = trip_low;
> > +
> > + if (trip_temp > tz->temperature && trip_temp < high)
> > + high = trip_temp;
> > + }
> > +
> > + /* No need to change trip points */
> > + if (tz->prev_low_trip == low && tz->prev_high_trip == high)
> > + goto exit;
> > +
> > + tz->prev_low_trip = low;
> > + tz->prev_high_trip = high;
> > +
> > + dev_dbg(&tz->device, "new temperature boundaries: %d < x <
> > %d\n",
> > + low, high);
> > +
> > + /*
> > +  * Set a temperature window. When this window is left the
> > driver
> > +  * must inform the thermal core via
> > thermal_zone_device_update.
> > +  */
> > + ret = tz->ops->set_trips(tz, low, high);
> > + if (ret)
> > + dev_err(&tz->device, "Failed to set trips: %d\n",
> > ret);
> > +
> > +exit:
> > + mutex_unlock(&tz->lock);
> > +}
> > +EXPORT_SYMBOL_GPL(thermal_zone_set_trips);
> > +
> >  static void update_temperature(struct thermal_zone_device *tz)
> >  {
> >   int temp, ret;
> > @@ -417,6 +467,8 @@ void thermal_zone_device_update(struct
> > thermal_zone_device *tz)
> >
> >   update_temperature(tz);
> >
> > + thermal_zone_set_trips(tz);
> > +
> >   for (count = 0; count < tz->trips; count++)
> >   handle_thermal_trip(tz, count);
> >  }
> > @@ -1175,6 +1227,8 @@ thermal_zone_device_register(const char *type,
> > int trips, int mask,
> >   tz->trips = trips;
> >   tz->passive_delay = passive_delay;
> >   tz->polling_delay = polling_delay;
> > + tz->prev_low_trip = INT_MAX;
> > + tz->prev_high_trip = -INT_MAX;
> >
> >   /* sys I/F */
> >   /* Add nodes that are always present via .groups */
> > diff --git a/drivers/thermal/thermal_sysfs.c
> > b/drivers/thermal/thermal_sysfs.c
> > index 743df50..33bbe30 100644
> > --- a/drivers/thermal/thermal_sysfs.c
> > +++ b/drivers/thermal/thermal_sysfs.c
> > @@ -219,6 +219,9 @@ trip_point_hyst_store(struct device *dev, struct
> > device_attribute *attr,
> >   ret = tz->ops->set_trip_hyst(tz, trip, temperature);
> >   mutex_unlock(&tz->lock);
> >
> > + if (!ret)
> > + thermal_zone_set_trips(tz);
> > +
> >   return ret ? ret : count;
> >  }
> >
> > diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> > index ea667b6..780e69d 100644
> > --- a/include/linux/thermal.h
> > +++ b/include/linux/thermal.h
> > @@ -99,6 +99,7 @@ struct thermal_zone_device_ops {
> >   int (*unbind) (struct thermal_zone_device *,
> >          struct thermal_cooling_device *);
> >   int (*get_temp) (struct thermal_zone_device *, int *);
> > + int (*set_trips) (struct thermal_zone_device *, int, int);
> >   int (*get_mode) (struct thermal_zone_device *,
> >    enum thermal_device_mode *);
> >   int (*set_mode) (struct thermal_zone_device *,
> > @@ -169,6 +170,10 @@ struct thermal_attr {
> >   * @last_temperature: previous temperature read
> >   * @emul_temperature: emulated temperature when using
> > CONFIG_THERMAL_EMULATION
> >   * @passive: 1 if you've crossed a passive trip
> > point, 0 otherwise.
> > + * @prev_low_trip: the low current temperature if you've
> > crossed a passive
> > + 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.
> > @@ -201,6 +206,8 @@ struct thermal_zone_device {
> >   int last_temperature;
> >   int emul_temperature;
> >   int passive;
> > + int prev_low_trip;
> > + int prev_high_trip;
> >   unsigned int forced_passive;
> >   atomic_t need_update;
> >   struct thermal_zone_device_ops *ops;
> > @@ -428,6 +435,7 @@ int thermal_zone_bind_cooling_device(struct
> > thermal_zone_device *, int,
> >  int thermal_zone_unbind_cooling_device(struct thermal_zone_device *,
> > int,
> >          struct thermal_cooling_device
> > *);
> >  void thermal_zone_device_update(struct thermal_zone_device *);
> > +void thermal_zone_set_trips(struct thermal_zone_device *);
> >
> >  struct thermal_cooling_device *thermal_cooling_device_register(char
> > *, void *,
> >   const struct thermal_cooling_device_ops *);
> > @@ -477,6 +485,8 @@ static inline int
> > thermal_zone_unbind_cooling_device(
> >  { return -ENODEV; }
> >  static inline void thermal_zone_device_update(struct
> > thermal_zone_device *tz)
> >  { }
> > +static inline void thermal_zone_set_trips(struct thermal_zone_device
> > *tz)
> > +{ }
> >  static inline struct thermal_cooling_device *
> >  thermal_cooling_device_register(char *type, void *devdata,
> >   const struct thermal_cooling_device_ops *ops)