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

From: Caesar Wang
Date: Tue May 24 2016 - 23:27:40 EST

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

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(+)
+ /*
+ * 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)
+ 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

Okay, done.


unsigned int forced_passive;
atomic_t need_update;
struct thermal_zone_device_ops *ops;

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