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([2402:f000:1:1501:200:5efe:a66f:470f]) by smtp.gmail.com with ESMTPSA id f8-v6sm296416ioq.10.2018.08.28.02.06.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 28 Aug 2018 02:06:04 -0700 (PDT) Subject: Re: [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power_off() To: Johan Hovold , Alexandre Belloni Cc: j-keerthy@ti.com, a.zummo@towertech.it, linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20180730135314.9336-1-baijiaju1990@gmail.com> <20180827205517.GD24549@piout.net> <20180828084940.GA28861@localhost> From: Jia-Ju Bai Message-ID: <72f42d57-90d1-83d5-3d1d-e82a2250a8ff@gmail.com> Date: Tue, 28 Aug 2018 17:06:00 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <20180828084940.GA28861@localhost> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/8/28 16:49, Johan Hovold wrote: > On Mon, Aug 27, 2018 at 10:55:17PM +0200, Alexandre Belloni wrote: >> Hi, >> >> On 30/07/2018 21:53:14+0800, Jia-Ju Bai wrote: >>> omap_rtc_power_off() is never called in atomic context. >>> It calls mdelay() to busily wait, which is not necessary. >>> mdelay() can be replaced with msleep(). >>> >>> This is found by a static analysis tool named DCNS written by myself. >>> >>> Signed-off-by: Jia-Ju Bai >>> --- >>> drivers/rtc/rtc-omap.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c >>> index 39086398833e..ef3d09525d0f 100644 >>> --- a/drivers/rtc/rtc-omap.c >>> +++ b/drivers/rtc/rtc-omap.c >>> @@ -476,7 +476,7 @@ static void omap_rtc_power_off(void) >>> * power off the system. Add a 500 ms margin for external latencies >>> * (e.g. debounce circuits). >>> */ >>> - mdelay(2500); >>> + msleep(2500); >> I'm not sure about that one because this is a poweroff function so it >> doesn't really make sense to sleep versus busy waiting (all the drivers >> in power/reset use mdelay()) > This power-off handler is called with interrupts disabled (as mentioned > in the function header) and must not sleep. Thanks for your reply :) I check the code again, and find that you are right. Sorry for my incorrect report. Best wishes, Jia-Ju Bai