From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752759AbbERJHS (ORCPT ); Mon, 18 May 2015 05:07:18 -0400 Received: from mail.kapsi.fi ([217.30.184.167]:46442 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752275AbbERJHM (ORCPT ); Mon, 18 May 2015 05:07:12 -0400 Message-ID: <5559ABAA.6040001@kapsi.fi> Date: Mon, 18 May 2015 12:06:50 +0300 From: Mikko Perttunen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Sascha Hauer , linux-pm@vger.kernel.org CC: Zhang Rui , Eduardo Valentin , linux-kernel@vger.kernel.org, Stephen Warren , kernel@pengutronix.de, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Brian Norris Subject: Re: [PATCH 11/15] thermal: thermal: Add support for hardware-tracked trip points References: <1431507163-19933-1-git-send-email-s.hauer@pengutronix.de> <1431507163-19933-12-git-send-email-s.hauer@pengutronix.de> In-Reply-To: <1431507163-19933-12-git-send-email-s.hauer@pengutronix.de> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:708:30:12d0:beee:7bff:fe5b:f272 X-SA-Exim-Mail-From: mikko.perttunen@kapsi.fi X-SA-Exim-Scanned: No (on mail.kapsi.fi); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks for picking up this patch :) Sorry for being late with these, but here's a few comments.. On 05/13/2015 11:52 AM, Sascha Hauer wrote: > 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 > --- > drivers/thermal/thermal_core.c | 43 ++++++++++++++++++++++++++++++++++++++++++ > include/linux/thermal.h | 3 +++ > 2 files changed, 46 insertions(+) > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c > index 6bbf61f..3ae1795 100644 > --- a/drivers/thermal/thermal_core.c > +++ b/drivers/thermal/thermal_core.c > @@ -453,6 +453,45 @@ int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp) > } > 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; > + > + if (!tz->ops->set_trips) > + return; > + > + /* No need to change trip points */ > + if (temp > tz->prev_low_trip && temp < tz->prev_high_trip) > + 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; > + } > + > + tz->prev_low_trip = low; > + tz->prev_high_trip = high; > + > + dev_dbg(&tz->device, "new temperature boundaries: %d < x < %d\n", > + low, high); > + > + tz->ops->set_trips(tz, low, high); This should probably do something if set_trips returns an error code; at least an error message, perhaps enable polling? I'm not exactly sure what safety features the thermal framework has in general if errors happen.. One interesting thing I noticed was that at least the bang-bang governor only acts if the temperature is properly smaller than (trip temp - hysteresis). So perhaps we should specify the non-tripping range as [low, high)? Or we could change bang-bang. > +} > + > void thermal_zone_device_update(struct thermal_zone_device *tz) > { > int temp, ret, count; > @@ -479,6 +518,8 @@ void thermal_zone_device_update(struct thermal_zone_device *tz) > dev_dbg(&tz->device, "last_temperature=%d, current_temperature=%d\n", > tz->last_temperature, tz->temperature); > > + thermal_zone_set_trips(tz); > + > for (count = 0; count < tz->trips; count++) > handle_thermal_trip(tz, count); > } set_trips should also be called from temp_store and other places that modify values that affect the trip points. > @@ -1494,6 +1535,8 @@ 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; > > dev_set_name(&tz->device, "thermal_zone%d", tz->id); > result = device_register(&tz->device); > diff --git a/include/linux/thermal.h b/include/linux/thermal.h > index 07bd5e8..aef6e13 100644 > --- a/include/linux/thermal.h > +++ b/include/linux/thermal.h > @@ -87,6 +87,7 @@ 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 *, > @@ -180,6 +181,8 @@ struct thermal_zone_device { > int last_temperature; > int emul_temperature; > int passive; > + int prev_low_trip; > + int prev_high_trip; > unsigned int forced_passive; > const struct thermal_zone_device_ops *ops; > const struct thermal_zone_params *tzp; >