From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753732AbaKZXML (ORCPT ); Wed, 26 Nov 2014 18:12:11 -0500 Received: from hqemgate14.nvidia.com ([216.228.121.143]:12224 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752526AbaKZXMG convert rfc822-to-8bit (ORCPT ); Wed, 26 Nov 2014 18:12:06 -0500 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Wed, 26 Nov 2014 15:10:41 -0800 Message-ID: <54765E5C.4000901@nvidia.com> Date: Wed, 26 Nov 2014 15:12:28 -0800 From: navneet kumar User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.2 MIME-Version: 1.0 To: Guenter Roeck , Eduardo Valentin , Lukasz Majewski CC: Zhang Rui , Linux PM list , Thierry Reding , Bartlomiej Zolnierkiewicz , Lukasz Majewski , Mikko Perttunen , Stephen Warren , Abhilash Kesavan , Abhilash Kesavan , , Caesar Wang Subject: Re: [PATCH v2 3/4] thermal: of: Extend of-thermal to export table of trip points References: <1412872737-624-1-git-send-email-l.majewski@samsung.com> <1416500488-7232-1-git-send-email-l.majewski@samsung.com> <1416500488-7232-4-git-send-email-l.majewski@samsung.com> <20141125203629.GA14292@developer> <20141126093510.4233ff7f@amdc2363> <20141126151828.GC3925@developer> <54763B66.90208@nvidia.com> <54764255.9040404@roeck-us.net> In-Reply-To: <54764255.9040404@roeck-us.net> X-Originating-IP: [172.17.185.249] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL104.nvidia.com (172.18.146.11) Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/26/2014 01:12 PM, Guenter Roeck wrote: > On 11/26/2014 12:43 PM, navneet kumar wrote: >> >> Hi Eduardo, Lukasz, >> >> [Combining my concerns as a single text blob here] >> >> I. Firstly, with the current patch >> 1. is it really needed to duplicate the struct thermal_trip? Why >> don’t >> we get rid of the __thermal_trip and stay with the 'thermal_trip' >> ? it >> is not a big change. >> >> 2. gtrips is not updated on "set_trip_temp" etc. actions via >> sysfs. (am >> I missing something?). >> >> II. The other concern is more of a design question >> 1. Do we intend to keep the of-thermal as a middle layer between the >> thermal_core and the sensor device? OR, is the role of of-thermal >> just >> to parse the DT and opt out ? currently of-thermal is somewhat a >> hybrid >> of these as, in addition to parsing the dt, it holds on to the data >> related to trip points etc. etc. >> >> 2. assuming latter is true (OF is just a dt parser helper): we should >> not be adding more intelligence and dependencies linked to the OF. >> >> 3. assuming former is true (OF is a well-defined middle layer): >> All is >> good till the point OF maintains the trip points (which is a good >> thing >> since, OF caches on to the data); BUT, if we expose this >> information to >> the sensor device too (as this patch is doing), >> >> 3a. we violate the layering principle :-) >> >> 3b. more importantly, this is all just excessive logic that we >> put in which *could be useful* only if we intend to extend the >> role of OF as a trip point management layer that does more than >> just holding on to the data. This may include - >> >> -> The sensor devices to know nothing about the >> trip_points, instead the sensor devices would work on >> "temperature thresholds" and OF would map sensor >> thresholds to the actual trip points as needed >> (configured from DT); while the sensor devices stick to >> using "thresholds". >> >> -> Queuing from above, sensors, most of the time, only >> need to know a high and a low temp threshold; which >> essentially is a subset of the active/passive etc. trip >> points. Calculation of that based on the current temp, >> as of today is replicated across all the sensor drivers >> and can be hoisted up to the of-thermal. >> > > Sorry, lost you here. What replicated calculation do you refer to ? > > Thanks, > Guenter > Some sensors have an ability to generate interrupts based upon a configured high and low temp thresholds/values. Once any of these limits is crossed, the sensor hardware has to be reconfigured with a new set of such values. I'll try to explain with an example - consider trip points TP1, TP2, TP3, TP4 sorted as low to high; and the current temp T1 such that - TP2> Seems like this is the opportune time to make a call about the role of >> of-thermal? >> >> On 11/26/2014 07:18 AM, Eduardo Valentin wrote: >>> * PGP Signed by an unknown key >>> >>> Hello, >>> >>> On Wed, Nov 26, 2014 at 09:35:10AM +0100, Lukasz Majewski wrote: >>>> Hi Eduardo, >>>> >>>>> Hello Lukasz, >>>>> >>>>> On Thu, Nov 20, 2014 at 05:21:27PM +0100, Lukasz Majewski wrote: >>>>>> This patch extends the of-thermal.c to export copy of trip points >>>>>> for a given thermal zone. >>>>>> >>>>>> Thermal drivers should use of_thermal_get_trip_points() method to >>>>>> get pointer to table of thermal trip points. >>>>>> >>>>>> Signed-off-by: Lukasz Majewski >>>>>> --- >>>>>> Changes for v2: >>>>>> - New patch - as suggested by Eduardo Valentin >>>>>> --- >>>>>> drivers/thermal/of-thermal.c | 33 >>>>>> +++++++++++++++++++++++++++++++++ drivers/thermal/thermal_core.h | >>>>>> 7 +++++++ include/linux/thermal.h | 14 ++++++++++++++ >>>>>> 3 files changed, 54 insertions(+) >>>>>> >>>>>> diff --git a/drivers/thermal/of-thermal.c >>>>>> b/drivers/thermal/of-thermal.c index 336af7f..33921c5 100644 >>>>>> --- a/drivers/thermal/of-thermal.c >>>>>> +++ b/drivers/thermal/of-thermal.c >>>>>> @@ -89,6 +89,7 @@ struct __thermal_zone { >>>>>> /* trip data */ >>>>>> int ntrips; >>>>>> struct __thermal_trip *trips; >>>>>> + struct thermal_trip *gtrips; >> Do we really need this duplication ? >>>>>> >>>>>> /* cooling binding data */ >>>>>> int num_tbps; >>>>>> @@ -152,6 +153,27 @@ bool of_thermal_is_trip_en(struct >>>>>> thermal_zone_device *tz, int trip) return true; >>>>>> } >>>>>> >>>>>> +/** >>>>>> + * of_thermal_get_trip_points - function to get access to a >>>>>> globally exported >>>>>> + * trip points >>>>>> + * >>>>>> + * @tz: pointer to a thermal zone >>>>>> + * >>>>>> + * This function provides a pointer to the copy of trip points >>>>>> table >>>>>> + * >>>>>> + * Return: pointer to trip points table, NULL otherwise >>>>>> + */ >>>>>> +const struct thermal_trip * const >>>>>> +of_thermal_get_trip_points(struct thermal_zone_device *tz) >>>>>> +{ >>>>>> + struct __thermal_zone *data = tz->devdata; >>>>>> + >>>>>> + if (!data) >>>>>> + return NULL; >>>>>> + >>>>>> + return data->gtrips; >>>>>> +} >>>>>> + >>>>> >>>>> EXPORT_SYMBOL_GPL(of_thermal_get_trip_points); >>>> >>>> Ok. >>>> >>>>> >>>>>> static int of_thermal_get_trend(struct thermal_zone_device *tz, >>>>>> int trip, enum thermal_trend *trend) >>>>>> { >>>>>> @@ -767,6 +789,16 @@ thermal_of_build_thermal_zone(struct >>>>>> device_node *np) goto free_tbps; >>>>>> } >>>>>> >>>>>> + tz->gtrips = kcalloc(tz->ntrips, sizeof(*tz->gtrips), >>>>>> GFP_KERNEL); >>>>>> + if (!tz->gtrips) { >>>>>> + ret = -ENOMEM; >>>>>> + goto free_tbps; >>>>>> + } >>>>>> + >>>>>> + for (i = 0; i < tz->ntrips; i++) >>>>>> + memcpy(&(tz->gtrips[i]), >>>>>> &(tz->trips[i].temperature), >>>>>> + sizeof(*tz->gtrips)); >>>>>> + >>>>>> finish: >>>>>> of_node_put(child); >>>>>> tz->mode = THERMAL_DEVICE_DISABLED; >>>>>> @@ -793,6 +825,7 @@ static inline void of_thermal_free_zone(struct >>>>>> __thermal_zone *tz) { >>>>>> int i; >>>>>> >>>>>> + kfree(tz->gtrips); >>>>>> for (i = 0; i < tz->num_tbps; i++) >>>>>> of_node_put(tz->tbps[i].cooling_device); >>>>>> kfree(tz->tbps); >> Couldn't find the code that updates *gtrips as a result of >> set_trip_temp via >> sysfs. >> >>>>>> diff --git a/drivers/thermal/thermal_core.h >>>>>> b/drivers/thermal/thermal_core.h index 466208c..a9580ca 100644 >>>>>> --- a/drivers/thermal/thermal_core.h >>>>>> +++ b/drivers/thermal/thermal_core.h >>>>>> @@ -91,6 +91,8 @@ int of_parse_thermal_zones(void); >>>>>> void of_thermal_destroy_zones(void); >>>>>> int of_thermal_get_ntrips(struct thermal_zone_device *); >>>>>> bool of_thermal_is_trip_en(struct thermal_zone_device *, int); >>>>>> +const struct thermal_trip * const >>>>>> +of_thermal_get_trip_points(struct thermal_zone_device *); >>>>>> #else >>>>>> static inline int of_parse_thermal_zones(void) { return 0; } >>>>>> static inline void of_thermal_destroy_zones(void) { } >>>>>> @@ -102,6 +104,11 @@ static inline bool >>>>>> of_thermal_is_trip_en(struct thermal_zone_device *, int) { >>>>> >>>>> This produces compilation error when CONFIG_THERMAL_OF is not set. >>>>> Name the parameters to fix. >>>> >>>> As all the other cases, I will fix that. >>>> >>>>> >>>>>> return 0; >>>>>> } >>>>>> +static inline const struct thermal_trip * const >>>>>> +of_thermal_get_trip_points(struct thermal_zone_device *) >>>>>> +{ >>>>>> + return NULL; >>>>>> +} >>>>>> #endif >>>>>> >>>>>> #endif /* __THERMAL_CORE_H__ */ >>>>>> diff --git a/include/linux/thermal.h b/include/linux/thermal.h >>>>>> index 5bc28a7..88d7249 100644 >>>>>> --- a/include/linux/thermal.h >>>>>> +++ b/include/linux/thermal.h >>>>>> @@ -303,6 +303,20 @@ struct thermal_zone_of_device_ops { >>>>>> int (*get_trend)(void *, long *); >>>>>> }; >>>>>> >>>>>> +/** >>>>>> + * struct thermal_trip - Structure representing themal trip points >>>>>> exported from >>>>>> + * of-thermal >>>>>> + * >>>>> >>>>> The only problem I have with this name is that would look like it is >>>>> in use in all thermal framework, which is not really the case. But I >>>>> do think having a type here is a good thing. So, not sure :-) >>>> >>>> It can stay to be struct thermal_trip or we can rename it to >>>> struct of_thermal_trip. >>>> >>>> I'm fine with both names. >>> >>> Leave it as 'thermal_trip'. >>> >>>> >>>>> >>>>>> + * @temperature: trip point temperature >>>>>> + * @hysteresis: trip point hysteresis >>>>>> + * @type: trip point type >>>>>> + */ >>>>>> +struct thermal_trip { >>>>>> + unsigned long int temperature; >>>>>> + unsigned long int hysteresis; >>>>>> + enum thermal_trip_type type; >>>>>> +}; >>>>>> + >>>>>> /* Function declarations */ >>>>>> #ifdef CONFIG_THERMAL_OF >>>>>> struct thermal_zone_device * >>>>>> -- >>>>>> 2.0.0.rc2 >>>>>> >>>> >>>> >>>> >>>> -- >>>> Best regards, >>>> >>>> Lukasz Majewski >>>> >>>> Samsung R&D Institute Poland (SRPOL) | Linux Platform Group >>> >>> * Unknown Key >>> * 0x7DA4E256 >>> >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/