From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751797AbeDKFaY (ORCPT ); Wed, 11 Apr 2018 01:30:24 -0400 Received: from anchovy2.45ru.net.au ([203.30.46.146]:48358 "EHLO anchovy2.45ru.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750797AbeDKFaX (ORCPT ); Wed, 11 Apr 2018 01:30:23 -0400 Subject: Re: [PATCH] net: dsa: b53: Replace mdelay with msleep in b53_switch_reset_gpio To: Jia-Ju Bai , f.fainelli@gmail.com, andrew@lunn.ch, vivien.didelot@savoirfairelinux.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <1523411485-2030-1-git-send-email-baijiaju1990@gmail.com> From: Phil Reid Message-ID: <11d079ab-3c07-a10d-c321-f873c53e9690@electromag.com.au> Date: Wed, 11 Apr 2018 13:30:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <1523411485-2030-1-git-send-email-baijiaju1990@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-AU Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/04/2018 09:51, Jia-Ju Bai wrote: > b53_switch_reset_gpio() is never called in atomic context. > > The call chain ending up at b53_switch_reset_gpio() is: > [1] b53_switch_reset_gpio() <- b53_switch_reset() <- > b53_reset_switch() <- b53_setup() > > b53_switch_reset_gpio() is set as ".setup" in struct dsa_switch_ops. > This function is not called in atomic context. > > Despite never getting called from atomic context, b53_switch_reset_gpio() > calls mdelay() to busily wait. > This is not necessary and can be replaced with msleep() to > avoid busy waiting. > > This is found by a static analysis tool named DCNS written by myself. > And I also manually check it. > > Signed-off-by: Jia-Ju Bai > --- > drivers/net/dsa/b53/b53_common.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c > index 274f367..e070ff6 100644 > --- a/drivers/net/dsa/b53/b53_common.c > +++ b/drivers/net/dsa/b53/b53_common.c > @@ -597,10 +597,10 @@ static void b53_switch_reset_gpio(struct b53_device *dev) > /* Reset sequence: RESET low(50ms)->high(20ms) > */ > gpio_set_value(gpio, 0); > - mdelay(50); > + msleep(50); > > gpio_set_value(gpio, 1); > - mdelay(20); > + msleep(20); > > dev->current_page = 0xff; > } > Would that also imply gpio_set_value could be gpio_set_value_cansleep? -- Regards Phil Reid