Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752721AbdIBNLf (ORCPT ); Sat, 2 Sep 2017 09:11:35 -0400 Received: from mail-wm0-f52.google.com ([74.125.82.52]:38253 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752626AbdIBNLe (ORCPT ); Sat, 2 Sep 2017 09:11:34 -0400 X-Google-Smtp-Source: ADKCNb6p/C5AsyVWZfKtWSiIl0bnW3Z+FaeMgw7yMyIkTZZdUGLzvuyvNFeB8x8Vzld1QlNuPjocMQ== Subject: Re: [PATCH 13/13] thermal/drivers/hisi: Remove mutex_lock in the code To: Leo Yan Cc: rui.zhang@intel.com, edubezval@gmail.com, linux-pm@vger.kernel.org, kevin.wangtao@linaro.org, open list References: <1504082857-21702-1-git-send-email-daniel.lezcano@linaro.org> <1504082857-21702-13-git-send-email-daniel.lezcano@linaro.org> <20170902040456.GE3841@leoy-linaro> From: Daniel Lezcano Message-ID: <1e05ccb1-45b1-1b16-cab4-8a28dbfd4f9e@linaro.org> Date: Sat, 2 Sep 2017 15:11:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170902040456.GE3841@leoy-linaro> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2869 Lines: 83 On 02/09/2017 06:04, Leo Yan wrote: > On Wed, Aug 30, 2017 at 10:47:37AM +0200, Daniel Lezcano wrote: >> The mutex is used to protect against writes in the configuration register. >> >> That happens at probe time, with no possible race yet. >> >> Then when the module is unloaded and at suspend/resume. >> >> When the module is unloaded, it is an userspace operation, thus via a process. >> Suspending the system goes through the freezer to suspend all the tasks >> synchronously before continuing. So it is not possible to hit the suspend ops >> in this driver while we are unloading it. >> >> The resume is the same situation than the probe. >> >> In other words, even if there are several places where we write the >> configuration register, there is no situation where we can write it at the same >> time, so far as I can judge > > After applied your previous patches, configuration reigster accessing > only happens in the probe and resume functions. So shouldn't have > chance to access it at the same time. > > BTW, I verified this patch with system suspend/resume, so far it works > well after system resume back. Great, thanks for testing this. >> Signed-off-by: Daniel Lezcano > > Reviewed-by: Leo Yan > Tested-by: Leo Yan > >> --- >> drivers/thermal/hisi_thermal.c | 6 ------ >> 1 file changed, 6 deletions(-) >> >> diff --git a/drivers/thermal/hisi_thermal.c b/drivers/thermal/hisi_thermal.c >> index b1b086ab..b9e8ee2 100644 >> --- a/drivers/thermal/hisi_thermal.c >> +++ b/drivers/thermal/hisi_thermal.c >> @@ -51,7 +51,6 @@ struct hisi_thermal_sensor { >> }; >> >> struct hisi_thermal_data { >> - struct mutex thermal_lock; /* protects register data */ >> struct platform_device *pdev; >> struct clk *clk; >> struct hisi_thermal_sensor sensor; >> @@ -196,14 +195,10 @@ static inline void hisi_thermal_hdak_set(void __iomem *addr, int value) >> >> static void hisi_thermal_disable_sensor(struct hisi_thermal_data *data) >> { >> - mutex_lock(&data->thermal_lock); >> - >> /* disable sensor module */ >> hisi_thermal_enable(data->regs, 0); >> hisi_thermal_alarm_enable(data->regs, 0); >> hisi_thermal_reset_enable(data->regs, 0); >> - >> - mutex_unlock(&data->thermal_lock); >> } >> >> static int hisi_thermal_get_temp(void *__data, int *temp) >> @@ -340,7 +335,6 @@ static int hisi_thermal_probe(struct platform_device *pdev) >> if (!data) >> return -ENOMEM; >> >> - mutex_init(&data->thermal_lock); >> data->pdev = pdev; >> >> res = platform_get_resource(pdev, IORESOURCE_MEM, 0); >> -- >> 2.7.4 >> -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog