From patchwork Sun Feb 19 14:36:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Lezcano X-Patchwork-Id: 654992 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 4D8FBC6FD1F for ; Sun, 19 Feb 2023 14:39:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230212AbjBSOjL (ORCPT ); Sun, 19 Feb 2023 09:39:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230250AbjBSOih (ORCPT ); Sun, 19 Feb 2023 09:38:37 -0500 Received: from mail-wr1-x436.google.com (mail-wr1-x436.google.com [IPv6:2a00:1450:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15D1211152 for ; Sun, 19 Feb 2023 06:38:14 -0800 (PST) Received: by mail-wr1-x436.google.com with SMTP id bp28so533276wrb.2 for ; Sun, 19 Feb 2023 06:38:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=xVzYorydu8I+vmR0UzViLt9Y2MhZrZxLWqtLEYveqhw=; b=aofmVeNA4acxVVgFs38ZTZRtGVg1wncseVSzDl5/8tQx4eux9fWRapy4cjcddqKUyj fSKV/ecXnrtBICF4qVNBzsCvINfrypeVjF9aCENYJbGpDzOYhGnyobwA9kXWxxOQACLG eIFdMAEjauS4L+ffvALgbZjl5wzOGCsySkz6XE8orKOTkdb/ciDEkS0E/wS5P/DyFruu VXmxTK+03qoIyIOpLLXfSsSgtZf/J+hrQ0KIr/9JiT7rVEZoTxdoyZNQR2kt1WXrTvhn HrAr4oKSfdr5CB4ulHVQFXWf/KX5kOQKdEIWklXPQgoQVSq2KH+AaTSr048RjW8Fdw3P yeLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=xVzYorydu8I+vmR0UzViLt9Y2MhZrZxLWqtLEYveqhw=; b=wX8jH953rZDugFVx855iKzjygDCEgMOdMwYu/hMuP/vrA1yC5McmZHlKEdq5j0NgwF uJBdtxfqUQPHi408VJSNbOcE60BJFwV1y1sveeOOmrJnfBv3x++j5L16pEeyzgg0wEvO 02N0KN1Yfa+q3skf2WsJK+az+zDjNcWQEJiB2/2TcauOEGhNQQdKNKS+WLb7c/PYXEeB 3Foume41yxRZRyLNeOfMM/z+DQwECgpHZtRW/aUJPi/qTGBvjnvcMsYNtoI8wZeCKIXa 1ZdaInPzxSrUFN3xLfhmGRkLXtjh5XR5qLsgkyw4ATp2+Jq0WymGovBkuT6cHDxQbwez qGrA== X-Gm-Message-State: AO0yUKWbtQvjzZjXaFshv7QMeuiQQIR1Dsh/1HfxynA6ZQp2+YlizEIx P6FPyNVktqTzUUEWX7fZXM8S4w== X-Google-Smtp-Source: AK7set9+IMytDQLX5f4z3vq8PuxTWU9aQeQD3QlYl1Tn6AoFc4WJCWv4N4Be9Np6y+/oDZjmFWXR3w== X-Received: by 2002:a05:6000:181:b0:2c5:49e1:b2cb with SMTP id p1-20020a056000018100b002c549e1b2cbmr1767154wrx.37.1676817493623; Sun, 19 Feb 2023 06:38:13 -0800 (PST) Received: from mai.box.freepro.com ([2a05:6e02:1041:c10:6f43:b92:7670:463]) by smtp.gmail.com with ESMTPSA id a18-20020adfe5d2000000b002be505ab59asm86176wrn.97.2023.02.19.06.38.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Feb 2023 06:38:13 -0800 (PST) From: Daniel Lezcano To: rafael@kernel.org, daniel.lezcano@linaro.org Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Amit Kucheria , Zhang Rui , Thierry Reding , Jonathan Hunter , =?utf-8?q?Niklas_S=C3=B6derlund?= , Florian Fainelli , Miquel Raynal , linux-tegra@vger.kernel.org (open list:TEGRA ARCHITECTURE SUPPORT) Subject: [PATCH v1 13/17] thermal/drivers/tegra: Remove unneeded lock when setting a trip point Date: Sun, 19 Feb 2023 15:36:53 +0100 Message-Id: <20230219143657.241542-14-daniel.lezcano@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230219143657.241542-1-daniel.lezcano@linaro.org> References: <20230219143657.241542-1-daniel.lezcano@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org The function tegra_tsensor_enable_hw_channel() takes the thermal zone lock to prevent "a potential" race with a call to set_trips() callback. The driver must not play with the thermal framework core code internals. The tegra_tsensor_enable_hw_channel() is called by: - the suspend / resume callbacks - the probe function after the thermal zones are registered The thermal zone lock taken in this function is supposed to protect from a call to the set_trips() callback which writes in the same register. The potential race is when suspend / resume are called at the same time as set_trips. This one is called only in thermal_zone_device_update(). - At suspend time, the 'in_suspend' is set, thus the thermal_zone_device_update() bails out immediately and set_trips is not called during this moment. - At resume time, the thermal zone is updated at PM_POST_SUSPEND, thus the driver has already set the TH2 temperature. - At probe time, we register the thermal zone and then we set the TH2. The only scenario I can see so far is the interrupt fires, the thermal_zone_update() is called exactly at the moment tegra_tsensor_enable_hw_channel() a few lines after registering it. Disable the interrupt before setting up the hw channels and then enable it. We close the potential race window without using the thermal zone's lock. Signed-off-by: Daniel Lezcano --- drivers/thermal/tegra/tegra30-tsensor.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/thermal/tegra/tegra30-tsensor.c b/drivers/thermal/tegra/tegra30-tsensor.c index ceb5b1b338a9..9cf74208673f 100644 --- a/drivers/thermal/tegra/tegra30-tsensor.c +++ b/drivers/thermal/tegra/tegra30-tsensor.c @@ -359,9 +359,6 @@ static int tegra_tsensor_enable_hw_channel(const struct tegra_tsensor *ts, tegra_tsensor_get_hw_channel_trips(tzd, &hot_trip, &crit_trip); - /* prevent potential racing with tegra_tsensor_set_trips() */ - mutex_lock(&tzd->lock); - dev_info_once(ts->dev, "ch%u: PMC emergency shutdown trip set to %dC\n", id, DIV_ROUND_CLOSEST(crit_trip, 1000)); @@ -404,8 +401,6 @@ static int tegra_tsensor_enable_hw_channel(const struct tegra_tsensor *ts, val |= FIELD_PREP(TSENSOR_SENSOR0_CONFIG0_INTR_THERMAL_RST_EN, 1); writel_relaxed(val, tsc->regs + TSENSOR_SENSOR0_CONFIG0); - mutex_unlock(&tzd->lock); - err = thermal_zone_device_enable(tzd); if (err) { dev_err(ts->dev, "ch%u: failed to enable zone: %d\n", id, err); @@ -592,12 +587,24 @@ static int tegra_tsensor_probe(struct platform_device *pdev) return dev_err_probe(&pdev->dev, err, "failed to request interrupt\n"); + /* + * Disable the interrupt so set_trips() can not be called + * while we are setting up the register + * TSENSOR_SENSOR0_CONFIG1. With this we close a potential + * race window where we are setting up the TH2 and the + * temperature hits TH1 resulting to an update of the + * TSENSOR_SENSOR0_CONFIG1 register in the ISR. + */ + disable_irq(irq); + for (i = 0; i < ARRAY_SIZE(ts->ch); i++) { err = tegra_tsensor_enable_hw_channel(ts, i); if (err) return err; } + enable_irq(irq); + return 0; }