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[85.230.190.116]) by smtp.gmail.com with ESMTPSA id v10-v6sm97054ljg.12.2018.08.28.01.49.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 28 Aug 2018 01:49:42 -0700 (PDT) Received: from johan by xi.terra with local (Exim 4.91) (envelope-from ) id 1fuZgy-0007ds-AZ; Tue, 28 Aug 2018 10:49:41 +0200 Date: Tue, 28 Aug 2018 10:49:40 +0200 From: Johan Hovold To: Alexandre Belloni Cc: Jia-Ju Bai , johan@kernel.org, j-keerthy@ti.com, a.zummo@towertech.it, linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rtc: rtc-omap: Replace mdelay() with msleep() in omap_rtc_power_off() Message-ID: <20180828084940.GA28861@localhost> References: <20180730135314.9336-1-baijiaju1990@gmail.com> <20180827205517.GD24549@piout.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180827205517.GD24549@piout.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Johan