From patchwork Thu Oct 19 17:05:58 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 10017835 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 027C5602C8 for ; Thu, 19 Oct 2017 17:09:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DF34728D55 for ; Thu, 19 Oct 2017 17:09:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D1BEE28DCE; Thu, 19 Oct 2017 17:09:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0F63828D55 for ; Thu, 19 Oct 2017 17:09:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755134AbdJSRJ2 (ORCPT ); Thu, 19 Oct 2017 13:09:28 -0400 Received: from mail-wm0-f45.google.com ([74.125.82.45]:47661 "EHLO mail-wm0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755101AbdJSRIy (ORCPT ); Thu, 19 Oct 2017 13:08:54 -0400 Received: by mail-wm0-f45.google.com with SMTP id t69so17363984wmt.2 for ; Thu, 19 Oct 2017 10:08:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=l9O69Zgu7L3MlYgYnT3L0ZtiItPcwtBEfH+iilZLcWQ=; b=QC+V8BwcHryhpJ6XG3FVTaMf1S2290K2df7leCY57/DFi0ZPbkwCBgcQovetXWHSJD Za0pgudRBsFXGogrDnrgiEz977tuHRwauaFoYX4FXaLLhW5ZaPy+KRMwlv/yjitbA1eU vkPgr44KH87Hth5dP9bGMkEWkzLNKveCs6Zus= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=l9O69Zgu7L3MlYgYnT3L0ZtiItPcwtBEfH+iilZLcWQ=; b=Ty1bxHfPJIZiZ6jMHafxj3yJ+JkkxgrIeg2mzxo6GthaRAdCxMA6C8Q484ooF96GAq nksDSS77G3MlcPrwdtm+9EX4JfzexIDzDaf4vPNUkCrAe0GBIUk+v2HARG7o6EcgCAzn 8qXdkElkOr6CK3bmizbp7oQdP1UO3wbnXMVxwQiN6fiKHyBIqLZbGIWiqqb7hIB450av rzPUK4DEYuC9qEv1pRbuIinp6eNifCjwS76W7IQ/YwCuM+oq8ld8YSkJIfAPoXfezjmk QIA9OFk5JX5ZDtQvZN/x2+obUxolA+gmpfSGkkNFpH0owoFAzPP6FQLBPIOzm+QdT4by 39LQ== X-Gm-Message-State: AMCzsaUstkUcV42TRCOqGrC/xl8I9em4s3o+VuZ2SsoEjybXJSDeWdp2 gx4kyb8+zdx2Rx8IFuoHsNgY+A== X-Google-Smtp-Source: ABhQp+S45k+Et5Dxj0a8T/gkRVeFsK2e3HuqDKvlFFwA7sFPGfXcBFAjRXaDqMWSCuNXPnDsNVUeBw== X-Received: by 10.28.199.75 with SMTP id x72mr2393090wmf.119.1508432932430; Thu, 19 Oct 2017 10:08:52 -0700 (PDT) Received: from localhost.localdomain ([2a01:e35:879a:6cd0:51c7:d9b7:e14b:6840]) by smtp.gmail.com with ESMTPSA id g16sm14277394wrd.72.2017.10.19.10.08.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 19 Oct 2017 10:08:51 -0700 (PDT) From: Daniel Lezcano To: edubezval@gmail.com, rui.zhang@intel.com Cc: linux-pm@vger.kernel.org, leo.yan@linaro.org, linux-kernel@vger.kernel.org, Keerthy , John Stultz Subject: [PATCH 16/18] thermal/drivers/step_wise: Fix temperature regulation misbehavior Date: Thu, 19 Oct 2017 19:05:58 +0200 Message-Id: <1508432760-17847-16-git-send-email-daniel.lezcano@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1508432760-17847-1-git-send-email-daniel.lezcano@linaro.org> References: <6ac48f08-7fe6-92e9-0801-6ed3bcd05ff1@linaro.org> <1508432760-17847-1-git-send-email-daniel.lezcano@linaro.org> MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP There is a particular situation when the cooling device is cpufreq and the heat dissipation is not efficient enough where the temperature increases little by little until reaching the critical threshold and leading to a SoC reset. The behavior is reproducible on a hikey6220 with bad heat dissipation (eg. stacked with other boards). Running a simple C program doing while(1); for each CPU of the SoC makes the temperature to reach the passive regulation trip point and ends up to the maximum allowed temperature followed by a reset. This issue has been also reported by running the libhugetlbfs test suite. What is observed is a ping pong between two cpu frequencies, 1.2GHz and 900MHz while the temperature continues to grow. It appears the step wise governor calls get_target_state() the first time with the throttle set to true and the trend to 'raising'. The code selects logically the next state, so the cpu frequency decreases from 1.2GHz to 900MHz, so far so good. The temperature decreases immediately but still stays greater than the trip point, then get_target_state() is called again, this time with the throttle set to true *and* the trend to 'dropping'. From there the algorithm assumes we have to step down the state and the cpu frequency jumps back to 1.2GHz. But the temperature is still higher than the trip point, so get_target_state() is called with throttle=1 and trend='raising' again, we jump to 900MHz, then get_target_state() is called with throttle=1 and trend='dropping', we jump to 1.2GHz, etc ... but the temperature does not stabilizes and continues to increase. [ 237.922654] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1 [ 237.922678] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=1 [ 237.922690] thermal cooling_device0: cur_state=0 [ 237.922701] thermal cooling_device0: old_target=0, target=1 [ 238.026656] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=2,throttle=1 [ 238.026680] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=2,throttle=1 [ 238.026694] thermal cooling_device0: cur_state=1 [ 238.026707] thermal cooling_device0: old_target=1, target=0 [ 238.134647] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1 [ 238.134667] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=1 [ 238.134679] thermal cooling_device0: cur_state=0 [ 238.134690] thermal cooling_device0: old_target=0, target=1 In this situation the temperature continues to increase while the trend is oscillating between 'dropping' and 'raising'. We need to keep the current state untouched if the throttle is set, so the temperature can decrease or a higher state could be selected, thus preventing this oscillation. Keeping the next_target untouched when 'throttle' is true at 'dropping' time fixes the issue. The following traces show the governor does not change the next state if trend==2 (dropping) and throttle==1. [ 2306.127987] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1 [ 2306.128009] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=1 [ 2306.128021] thermal cooling_device0: cur_state=0 [ 2306.128031] thermal cooling_device0: old_target=0, target=1 [ 2306.231991] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=2,throttle=1 [ 2306.232016] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=2,throttle=1 [ 2306.232030] thermal cooling_device0: cur_state=1 [ 2306.232042] thermal cooling_device0: old_target=1, target=1 [ 2306.335982] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=0,throttle=1 [ 2306.336006] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=0,throttle=1 [ 2306.336021] thermal cooling_device0: cur_state=1 [ 2306.336034] thermal cooling_device0: old_target=1, target=1 [ 2306.439984] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=2,throttle=1 [ 2306.440008] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=2,throttle=0 [ 2306.440022] thermal cooling_device0: cur_state=1 [ 2306.440034] thermal cooling_device0: old_target=1, target=0 [ ... ] After a while, if the temperature continues to increase, the next state becomes 2 which is 720MHz on the hikey. That results in the temperature stabilizing around the trip point. [ 2455.831982] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1 [ 2455.832006] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=0 [ 2455.832019] thermal cooling_device0: cur_state=1 [ 2455.832032] thermal cooling_device0: old_target=1, target=1 [ 2455.935985] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=0,throttle=1 [ 2455.936013] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=0,throttle=0 [ 2455.936027] thermal cooling_device0: cur_state=1 [ 2455.936040] thermal cooling_device0: old_target=1, target=1 [ 2456.043984] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=0,throttle=1 [ 2456.044009] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=0,throttle=0 [ 2456.044023] thermal cooling_device0: cur_state=1 [ 2456.044036] thermal cooling_device0: old_target=1, target=1 [ 2456.148001] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1 [ 2456.148028] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=1 [ 2456.148042] thermal cooling_device0: cur_state=1 [ 2456.148055] thermal cooling_device0: old_target=1, target=2 [ 2456.252009] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=2,throttle=1 [ 2456.252041] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=2,throttle=0 [ 2456.252058] thermal cooling_device0: cur_state=2 [ 2456.252075] thermal cooling_device0: old_target=2, target=1 IOW, this change is needed to keep the state for a cooling device if the temperature trend is oscillating while the temperature increases slightly. Without this change, the situation above leads to a catastrophic crash by a hardware reset on hikey. This issue has been reported to happen on an OMAP dra7xx also. Signed-off-by: Daniel Lezcano Cc: Keerthy Cc: John Stultz Cc: Leo Yan Tested-by: Keerthy Reviewed-by: Keerthy --- drivers/thermal/step_wise.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c index be95826..ee047ca 100644 --- a/drivers/thermal/step_wise.c +++ b/drivers/thermal/step_wise.c @@ -31,8 +31,7 @@ * If the temperature is higher than a trip point, * a. if the trend is THERMAL_TREND_RAISING, use higher cooling * state for this trip point - * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling - * state for this trip point + * b. if the trend is THERMAL_TREND_DROPPING, do nothing * c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit * for this trip point * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit @@ -94,9 +93,11 @@ static unsigned long get_target_state(struct thermal_instance *instance, if (!throttle) next_target = THERMAL_NO_TARGET; } else { - next_target = cur_state - 1; - if (next_target > instance->upper) - next_target = instance->upper; + if (!throttle) { + next_target = cur_state - 1; + if (next_target > instance->upper) + next_target = instance->upper; + } } break; case THERMAL_TREND_DROP_FULL: