Re: [PATCH v2 1/5] thermal: Add support for hardware-tracked trip points

[Caesar Wang]

Hi Javi,

Thanks your reviewing.

On 2016å05æ24æ 20:57, Javi Merino wrote:
> On Tue, May 03, 2016 at 05:33:29PM +0800, Caesar Wang wrote:
> > From: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> >
> > 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@xxxxxxxx>
> >
> > Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> > Signed-off-by: Caesar Wang <wxt@xxxxxxxxxxxxxx>
> > Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
> > Cc: Eduardo Valentin <edubezval@xxxxxxxxx>
> > Cc: linux-pm@xxxxxxxxxxxxxxx
> >
> > ---
> >
> > Changes in v2:
> > - update the sysfs-api.txt for set_trips
> >
> >   Documentation/thermal/sysfs-api.txt |  7 +++++
> >   drivers/thermal/thermal_core.c      | 52 +++++++++++++++++++++++++++++++++++++
> >   include/linux/thermal.h             |  3 +++
> >   3 files changed, 62 insertions(+)
<cut..>
> > +	/*
> > +	 * 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);
> This function can be called at the same time from multiple places so
> it should be reentrant.  I think you should call mutex_lock(tz->lock)
> before "if (tz->prev_low_trip == low && ..." and unlock it here.

Sound reasonable, fixes it in next version.

> > +}
> > +
> >   static void update_temperature(struct thermal_zone_device *tz)
> >   {
> >   	int temp, ret;
> > @@ -569,6 +614,8 @@ 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);
> >   }
> > @@ -754,6 +801,9 @@ trip_point_hyst_store(struct device *dev, struct device_attribute *attr,
> >   	 */
> >   	ret = tz->ops->set_trip_hyst(tz, trip, temperature);
> >   
> > +	if (!ret)
> > +		thermal_zone_set_trips(tz);
> > +
> You should add a similar call to thermal_zone_set_trips() in trip_point_temp_store()

No, this patch has been done.

if you see the linux next kernel.
72f3ada UPSTREAM: thermal: trip_point_temp_store() calls 
thermal_zone_device_update()

--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -733,8 +733,12 @@ trip_point_temp_store(struct device *dev, struct 
device_attribute *attr,
return -EINVAL;

ret = tz->ops->set_trip_temp(tz, trip, temperature);
+ if (ret)
+ return ret;

- return ret ? ret : count;
+ thermal_zone_device_update(tz);
+
+ return count;
}

So the "thermal_zone_set_trips(tz)" have been set in 
thermal_zone_device_update.

> >   	return ret ? ret : count;
> >   }
> >   
> > @@ -1843,6 +1893,8 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
> >   	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;
> >   	/* A new thermal zone needs to be updated anyway. */
> >   	atomic_set(&tz->need_update, 1);
> >   
> > diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> > index e45abe7..e258359 100644
> > --- a/include/linux/thermal.h
> > +++ b/include/linux/thermal.h
> > @@ -98,6 +98,7 @@ 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 *,
> > @@ -199,6 +200,8 @@ struct thermal_zone_device {
> >   	int last_temperature;
> >   	int emul_temperature;
> >   	int passive;
> > +	int prev_low_trip;
> > +	int prev_high_trip;
> Please document these fields in the kerneldoc comment before struct
> thermal_zone_device.

Okay, done.

Thanks!

-
Caesar
> >   	unsigned int forced_passive;
> >   	atomic_t need_update;
> >   	struct thermal_zone_device_ops *ops;
> Cheers,
> Javi
>
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