[PATCH v3 1/5] thermal: Add support for hardware-tracked trip points
Caesar Wang
wxt at rock-chips.com
Wed May 25 21:17:20 PDT 2016
On 2016年05月26日 08:34, Caesar Wang wrote:
>
> On 2016年05月26日 00:42, Javi Merino wrote:
>> Hi Caesar,
>>
>> On Wed, May 25, 2016 at 11:47:45AM +0800, Caesar Wang wrote:
>>> From: Sascha Hauer <s.hauer at 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 at kapsi.fi>
>>>
>>> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
>>> Signed-off-by: Caesar Wang <wxt at rock-chips.com>
>>> Cc: Zhang Rui <rui.zhang at intel.com>
>>> Cc: Eduardo Valentin <edubezval at gmail.com>
>>> Cc: linux-pm at vger.kernel.org
>>>
>>> ---
>>>
>>> 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 | 52
>>> +++++++++++++++++++++++++++++++++++++
>>> include/linux/thermal.h | 7 +++++
>>> 3 files changed, 66 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 5133cd1..e5bfbd3 100644
>>> --- a/drivers/thermal/thermal_core.c
>>> +++ b/drivers/thermal/thermal_core.c
>>> @@ -520,6 +520,51 @@ exit:
>>> }
>>> EXPORT_SYMBOL_GPL(thermal_zone_get_temp);
>>> +static void thermal_zone_set_trips(struct thermal_zone_device *tz)
>>> +{
>>> + int low = -INT_MAX;
>>> + int high = INT_MAX;
>>> + int trip_temp, hysteresis;
>>> + int temp = tz->temperature;
>>> + int i, ret;
>>> +
>>> + if (!tz->ops->set_trips)
>>> + return;
>>> +
>>> + 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 < temp && trip_low > low)
>>> + low = trip_low;
>>> +
>>> + if (trip_temp > temp && trip_temp < high)
>>> + high = trip_temp;
>>> + }
>>> +
>>> + /* No need to change trip points */
>>> + if (tz->prev_low_trip == low && tz->prev_high_trip == high)
>>> + return;
>>> +
>>> + 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);
>> In the v2 review
>> (http://article.gmane.org/gmane.linux.documentation/38442) you agreed
>> to add locking but you haven't done it. Maybe you sent the wrong
>> version?
>
> My god!
> Yep, I remember to change it. Somehow why ...
>
> Thanks Javi for looking over it.
>
> Hoping the next version is the final version.:-)
>
If add the lock, there is a deadlock for board, maybe I will keep to
stay with this version.
2.895038] [ INFO: possible recursive locking detected ]
[ 2.900459] 4.4.4 #56 Not tainted
[ 2.903774] ---------------------------------------------
[ 2.909171] swapper/0/1 is trying to acquire lock:
[ 2.913974] (&tz->lock){+.+.+.}, at: [<ffffffc00069b428>]
handle_thermal_trip+0x230/0x304
[ 2.922336]
[ 2.922336] but task is already holding lock:
[ 2.928166] (&tz->lock){+.+.+.}, at: [<ffffffc000699194>]
thermal_zone_set_trips+0xd8/0x180
[ 2.936670]
[ 2.936670] other info that might help us debug this:
[ 2.943199] Possible unsafe locking scenario:
[ 2.943199]
[ 2.949117] CPU0
[ 2.951565] ----
[ 2.954012] lock(&tz->lock);
[ 2.957098] lock(&tz->lock);
[ 2.960176]
[ 2.960176] *** DEADLOCK ***
[ 2.960176]
[ 2.966098] May be due to missing lock nesting notation
[ 2.966098]
[ 2.972885] 3 locks held by swapper/0/1:
[ 2.976809] #0: (&dev->mutex){......}, at: [<ffffffc0005920b0>]
__driver_attach+0x40/0xa8
[ 2.985243] #1: (&dev->mutex){......}, at: [<ffffffc0005920d8>]
__driver_attach+0x68/0xa8
[ 2.993671] #2: (&tz->lock){+.+.+.}, at: [<ffffffc000699194>]
thermal_zone_set_trips+0xd8/0x180
...
> -Caesar
>
>>
>> Cheers,
>> Javi
>>
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>
>
--
caesar wang | software engineer | wxt at rock-chip.com
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