From patchwork Fri Sep 8 09:05:02 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 112053 Delivered-To: patch@linaro.org Received: by 10.140.94.239 with SMTP id g102csp1257802qge; Fri, 8 Sep 2017 02:06:27 -0700 (PDT) X-Received: by 10.98.71.198 with SMTP id p67mr2375122pfi.15.1504861586949; Fri, 08 Sep 2017 02:06:26 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1504861586; cv=none; d=google.com; s=arc-20160816; b=gyj6QarO3wuNhycpQZgn1KR/L+MwefiPoYEo9OFosRPDBgq7nFK+G3bleobCLzY9KZ x40RErw1prevQiIhuXqJpy9rKZEvhZrcKmURjlOYnQbpcA4iDA/Cp4KpwyBgyZ+KI0NO u80RqvjmPwlhQae8AuSWv2Kl0tZQbChc3qd9/efzxuoA0gq+YDh6hbesTko0x8LYH0Ct QU2Bjw0znnawceAeukaebU6RW6OlVlbHkLthznNBm2vJSMQ+8oDvlvqcvwusZaSrQLNb 7xgyo9NmjP8qDKCAx6CvNz4IR4FSzhn2B2PUs2lh3k44GIv+SZAEoqBe3IoR0gbLLDfu YJuQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature:arc-authentication-results; bh=rszdTbfR5QHpsczkxkr9fH1gBOUQ6BSuCw2yikC4yoo=; b=jBFmOoo2AeqxhycD7g14EOVpQPAEO5uUSPMScGvXP4hX40IcqsLE5osIuFzGtaii4U 051ELzx2fnrk7JsXpTx2cPRxNZ43tpTf4XH3bsP+YztxYPt0ko/DXg6oAxWrjD5kBL4o roowgIN34J/hyJzfkwcEfCXsfVj6VbH9FHRpeCXDzW6rSocNittcvAHFtrCgEpf72qjE LsXN6RR3fT/ya/SSQHEBtVsNkQITEcJezS59V23c1gZNe1uXs3ay0DKK0YkJrsEu03MP nBEaDtr8qnLwkX/tBa3KCa9FhX/3PuSwaQNOZGEI80g+VZlXmwZ4pUEk4iIo4mB9XIV2 d3Yw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=TPiRNCkt; spf=pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-pm-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id m1si1343998pld.77.2017.09.08.02.06.26; Fri, 08 Sep 2017 02:06:26 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=TPiRNCkt; spf=pass (google.com: best guess record for domain of linux-pm-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-pm-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752089AbdIHJGZ (ORCPT + 12 others); Fri, 8 Sep 2017 05:06:25 -0400 Received: from mail-wm0-f51.google.com ([74.125.82.51]:45490 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750850AbdIHJGX (ORCPT ); Fri, 8 Sep 2017 05:06:23 -0400 Received: by mail-wm0-f51.google.com with SMTP id f199so955395wme.0 for ; Fri, 08 Sep 2017 02:06:22 -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=rszdTbfR5QHpsczkxkr9fH1gBOUQ6BSuCw2yikC4yoo=; b=TPiRNCktqfDmCTK4p+NMSMDR6fYAU84xdg9LQOeAcxztwEhBUxHUEF/MI7Hwqmws6H ghR3qiIhb7Sulk8BEUQMS1B6j9BxIFfJ2+c1IRHH5L0RSIHTAveWtKPqvNi7l2spIABS Cyyz80gnsxibx4cEHE1yNmRVshHr+aqO08m4Q= 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=rszdTbfR5QHpsczkxkr9fH1gBOUQ6BSuCw2yikC4yoo=; b=jLWE5px1Qj8lFI8OTiYrbxKzpVWTUbwBk0NrsY39vEjBaiE/YzKBq/CjNtdi2HnRJY GT4aYVi7FVeV37qvVqMhrTfhh6cHnOdCxQRDEKt3tbYGo4HWwKTiY1ngttv/XB6eDeo6 lU3hZZvwsEGLzz3YU3X7VgBd0Wph2knmHHrHhvfpnTr4caOpZVz9H7L6wOegDH95Y2aM Z99emK5ba5indrHBPcETfuaWTZlVk4ZCPFgLe52qgk9G1eQRyeBifTe7wQrq7ctcSRqX 8Vm2nbHRcHyzD1B1VU4Y/D/UbD0SWvFrU4uYeR0kA0BorDCRL9W6/fXA3LP0FMcSRLnZ LJZQ== X-Gm-Message-State: AHPjjUiBHCSAujw7vxhF6O0+CXGzivksZjD9q9NnpgGhK0jFBlZI4c8E SqsGpWbnxcCjrltOQoeuxi5azw== X-Google-Smtp-Source: AOwi7QAbjMp/VvPOGDBMlg1gI3paYsVYUfRRDRGGhBAw5n/8efBv3oGW6Y2tqhLxaQKzUlmAVtNb/A== X-Received: by 10.28.164.68 with SMTP id n65mr1114220wme.23.1504861582022; Fri, 08 Sep 2017 02:06:22 -0700 (PDT) Received: from localhost.localdomain ([2a01:e35:879a:6cd0:6426:ff85:17d6:f2f2]) by smtp.gmail.com with ESMTPSA id x17sm1224877wrg.50.2017.09.08.02.06.20 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 08 Sep 2017 02:06:21 -0700 (PDT) From: Daniel Lezcano To: rui.zhang@intel.com, edubezval@gmail.com Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, john.stultz@linaro.org, leo.yan@linaro.org, daniel.lezcano@linaro.org Subject: [PATCH V2] thermal/drivers/step_wise: Fix temperature regulation misbehavior Date: Fri, 8 Sep 2017 11:05:02 +0200 Message-Id: <1504861502-4093-1-git-send-email-daniel.lezcano@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <20170908030513.GC2755@localhost.localdomain> References: <20170908030513.GC2755@localhost.localdomain> MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 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 prevening 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. Signed-off-by: Daniel Lezcano --- drivers/thermal/step_wise.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) -- 2.7.4 diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c index bd2f133..703bd0d 100644 --- a/drivers/thermal/step_wise.c +++ b/drivers/thermal/step_wise.c @@ -95,9 +95,11 @@ 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: