Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751565AbdIBEFH (ORCPT ); Sat, 2 Sep 2017 00:05:07 -0400 Received: from mail-pf0-f170.google.com ([209.85.192.170]:35918 "EHLO mail-pf0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751428AbdIBEFG (ORCPT ); Sat, 2 Sep 2017 00:05:06 -0400 X-Google-Smtp-Source: ADKCNb6gxJ0kzkitUubHQZDnE3TIGQef54QcQuH21EbhWsFwBxCv+Z+E9wAqsCd032ZHTKgxPCk4RQ== Date: Sat, 2 Sep 2017 12:04:56 +0800 From: Leo Yan To: Daniel Lezcano Cc: rui.zhang@intel.com, edubezval@gmail.com, linux-pm@vger.kernel.org, kevin.wangtao@linaro.org, open list Subject: Re: [PATCH 13/13] thermal/drivers/hisi: Remove mutex_lock in the code Message-ID: <20170902040456.GE3841@leoy-linaro> References: <1504082857-21702-1-git-send-email-daniel.lezcano@linaro.org> <1504082857-21702-13-git-send-email-daniel.lezcano@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1504082857-21702-13-git-send-email-daniel.lezcano@linaro.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2490 Lines: 72 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. > 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 >