Javi, Thanks your comments. On 2016?06?03? 01:30, Javi Merino wrote: > Hi Caesar, > > On Fri, May 27, 2016 at 04:36:44PM +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 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 | 56 +++++++++++++++++++++++++++++++++++++ >> include/linux/thermal.h | 7 +++++ >> 3 files changed, 70 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..0591438 100644 >> --- a/drivers/thermal/thermal_core.c >> +++ b/drivers/thermal/thermal_core.c >> @@ -520,6 +520,55 @@ 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; > You only use the hysteresis for the low trip point and not for the > high trip point. Shouldn't you also add: > > trip_high = trip_temp + hysteresis; > > ... I don't think so, I think we didn't need add the for trip_high. We should triggle the trip points () in time when passive cooling, and throttle the frequency with the related governor. (After all that's used for high temperature) --- Maybe, we should think about the low temperature for thermal. (e.g. -10 degree, -20 degree....) The rockchip some SoCs have the hardware low temperature interrupts for thermal, but I haven't got up it. > >> + >> + if (trip_low < temp && trip_low > low) >> + low = trip_low; >> + >> + if (trip_temp > temp && trip_temp < high) >> + high = trip_temp; > ... and here: > > if (trip_high > temp && trip_high < high) > high = trip_high; Ditto >> + } >> + >> + /* No need to change trip points */ >> + if (tz->prev_low_trip == low && tz->prev_high_trip == high) >> + return; >> + >> + mutex_lock(&tz->lock); > I think you should get the lock for the whole function, including the > read of tz->temperature . I know I said that the lock should be > acquired before the if condition before but thinking about it, I think > there may be a race condition if userspace updates the hysteresis > while thermal_zone_device_update() is updating the temperature: you > could have the cpu that is updating the hysteresis seeing the old > temperature while the cpu that is updating the temperature would see > the old hysteresis. I think it's safer if this whole function is > protected from the lock, from the read of tz->temperature until the > end. Okay, I agree with you in here. :) Thanks. - Caesar > > Cheers, > Javi > >> + >> + 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); >> + >> + mutex_unlock(&tz->lock); >> +} >> + >> static void update_temperature(struct thermal_zone_device *tz) >> { >> int temp, ret; >> @@ -569,6 +618,8 @@ 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 +805,9 @@ 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); >> + >> return ret ? ret : count; >> } >> > _______________________________________________ > Linux-rockchip mailing list > Linux-rockchip at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-rockchip -- caesar wang | software engineer | wxt at rock-chip.com
