From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53472C433EF for ; Fri, 8 Jul 2022 03:56:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236767AbiGHD4y (ORCPT ); Thu, 7 Jul 2022 23:56:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230230AbiGHD4w (ORCPT ); Thu, 7 Jul 2022 23:56:52 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 66DF974DE7; Thu, 7 Jul 2022 20:56:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1657252611; x=1688788611; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=MYEPcE7pN1KciP37QC/kj2gcO7ZMO75h5cRFJHszhV8=; b=T6bOy/TvmUcr9pzFIzRgeCQMmXYKhBeTQ8Dt/rxvP1i94DOhdK3S/fVp hY6m+oy7umIiCKrkIq3eGWJjS7ILXy8zSryRZhJaRNlfax4TSC01zQ0hP fO8p9ltDUOFA3rPRvCLfn40yExfM4DpJZ0vdir170HcO+iNVBgxHv1+cy D9AH4l/osVoMGmt4DEDFRJS7mEXV61W8gbvaSla6mmQkYJPOJuCTRTMP3 4Z9slRF+kmMgXE6Y1K+cIHvXzSCgWKROPunjJvuTuHbZQEBf8WZqS8Yob KPtwbkBBmiyWciweBF5v+cAK4leLpyoE3tBzVvCiUlrzSv++xy2wLvB4J w==; X-IronPort-AV: E=McAfee;i="6400,9594,10401"; a="309744718" X-IronPort-AV: E=Sophos;i="5.92,254,1650956400"; d="scan'208";a="309744718" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jul 2022 20:56:50 -0700 X-IronPort-AV: E=Sophos;i="5.92,254,1650956400"; d="scan'208";a="544063323" Received: from lshi10-mobl.ccr.corp.intel.com ([10.249.172.47]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jul 2022 20:56:48 -0700 Message-ID: <6f8d449906a42ba11698d3c0ae9740b83f918f42.camel@intel.com> Subject: Re: [PATCH 3/3] thermal/core: Fix thermal trip cross point From: Zhang Rui To: Daniel Lezcano , rafael@kernel.org Cc: quic_manafm@quicinc.com, Amit Kucheria , "open list:THERMAL" , open list Date: Fri, 08 Jul 2022 11:56:45 +0800 In-Reply-To: <20220707214513.1133506-3-daniel.lezcano@linaro.org> References: <20220707214513.1133506-1-daniel.lezcano@linaro.org> <20220707214513.1133506-3-daniel.lezcano@linaro.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2022-07-07 at 23:45 +0200, Daniel Lezcano wrote: > The routine doing trip point crossing the way up or down is actually > wrong. > > A trip point is composed with a trip temperature and a hysteresis. > > The trip temperature is used to detect when the trip point is crossed > the way up. > > The trip temperature minus the hysteresis is used to detect when the > trip point is crossed the way down. > > > -----------low--------high------------| > > |<--------->| > | hyst | > | | > | -|--> crossed the way up > | > <---|-- crossed the way down > > For that, there is a two point comparison: the current temperature > and > the previous temperature. > > The actual code assumes if the current temperature is greater than > the > trip temperature and the previous temperature was lesser, then the > trip point is crossed the way up. That is true only if we crossed the > way down the low temperature boundary from the previous temperature > or > if the hysteresis is zero. The temperature can decrease between the > low and high, so the trip point is not crossed the way down and then > increase again and cross the high temperature raising a new trip > point > crossed detection which is incorrect. The same scenario happens when > crossing the way down. > > The trip point crossing the way up and down must act as parenthesis, > a > trip point down must close a trip point up. Today we have multiple > trip point up without the corresponding trip point down. > > In order to fix that, we store the previous trip point which gives > the > information about the previous trip. > > As a sidenote, the thermal_zone_device structure has already the > prev_trip_low and prev_trip_high information which are used by the > thermal_zone_set_trips() function. This one can be changed to be > triggered by the trip temperature crossing function, which makes more > sense, and the two fields will disappear. > > Signed-off-by: Daniel Lezcano > --- > drivers/thermal/thermal_core.c | 32 ++++++++++++++++++++++---------- > include/linux/thermal.h | 2 ++ > 2 files changed, 24 insertions(+), 10 deletions(-) > > diff --git a/drivers/thermal/thermal_core.c > b/drivers/thermal/thermal_core.c > index f66036b3daae..92bc9ddb6904 100644 > --- a/drivers/thermal/thermal_core.c > +++ b/drivers/thermal/thermal_core.c > @@ -357,19 +357,30 @@ static void handle_critical_trips(struct > thermal_zone_device *tz, > static void handle_thermal_trip_crossed(struct thermal_zone_device > *tz, int trip, > int trip_temp, int trip_hyst, > enum thermal_trip_type trip_type) > { > + int trip_low_temp = trip_temp - trip_hyst; > + > if (tz->last_temperature == THERMAL_TEMP_INVALID) > return; > > - if (tz->last_temperature < trip_temp && > - tz->temperature >= trip_temp) { > - thermal_notify_tz_trip_up(tz->id, trip, > - tz->temperature); > - } > - > - if (tz->last_temperature >= trip_temp && > - tz->temperature < (trip_temp - trip_hyst)) { > - thermal_notify_tz_trip_down(tz->id, trip, > - tz->temperature); > + /* > + * Due to the hysteresis, a third information is needed to > + * detect when the temperature is wavering between the > + * trip_low_temp and the trip_temp. A trip point is crossed > + * the way up only if the temperature is above it while the > + * previous temperature was below *and* we crossed the > + * trip_temp_low before. The previous trip point give us the > + * previous trip point transition. The similar problem exists > + * when crossing the way down. > + */ > + if (tz->last_temperature < trip_temp && tz->temperature >= > trip_temp && > + trip != tz->prev_trip) { > + thermal_notify_tz_trip_up(tz->id, trip, tz- > >temperature); > + tz->prev_trip = trip; > + > + } else if (tz->last_temperature >= trip_low_temp && tz- > >temperature < trip_low_temp && > + trip == tz->prev_trip) { > + thermal_notify_tz_trip_down(tz->id, trip, tz- > >temperature); > + tz->prev_trip = trip - 1; Say, let's assume hysteresis is Zero, When the temperature increases and we do thermal_notify_tz_trip_up() for trip 0 and trip 1, tz->prev_trip is set to 1 in this case. And then the temperature drops below trip 0, we don't have chance to do thermal_notify_tz_trip_down() for trip 0, because we always handle the trips in ascending order, and tz->prev_trip is 1 when we do handle_thermal_trip(0). thanks, rui > } > } > > @@ -427,6 +438,7 @@ static void thermal_zone_device_init(struct > thermal_zone_device *tz) > { > struct thermal_instance *pos; > tz->temperature = THERMAL_TEMP_INVALID; > + tz->prev_trip = -1; > tz->prev_low_trip = -INT_MAX; > tz->prev_high_trip = INT_MAX; > list_for_each_entry(pos, &tz->thermal_instances, tz_node) > diff --git a/include/linux/thermal.h b/include/linux/thermal.h > index 231bac2768fb..5b3bfb902d10 100644 > --- a/include/linux/thermal.h > +++ b/include/linux/thermal.h > @@ -124,6 +124,7 @@ struct thermal_cooling_device { > * @last_temperature: previous temperature read > * @emul_temperature: emulated temperature when using > CONFIG_THERMAL_EMULATION > * @passive: 1 if you've crossed a passive trip point, 0 > otherwise. > + * @prev_trip: previous trip point the thermal zone > was, -1 if below all of them > * @prev_low_trip: the low current temperature if you've crossed a > passive > trip point. > * @prev_high_trip: the above current temperature if you've crossed > a > @@ -159,6 +160,7 @@ struct thermal_zone_device { > int last_temperature; > int emul_temperature; > int passive; > + int prev_trip; > int prev_low_trip; > int prev_high_trip; > atomic_t need_update;