From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752773AbeDLBty (ORCPT ); Wed, 11 Apr 2018 21:49:54 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:37191 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751633AbeDLBtx (ORCPT ); Wed, 11 Apr 2018 21:49:53 -0400 X-Google-Smtp-Source: AIpwx4+P12DIov/x4cAkFqFUAHVwbkYnTw6qaMyZg8y17/wJgLUk8Gnj7LmrbjcbD0R25FyjO4ZMqA== Subject: Re: [PATCH] net: dsa: b53: Replace mdelay with msleep in b53_switch_reset_gpio To: Florian Fainelli , Phil Reid , 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> <11d079ab-3c07-a10d-c321-f873c53e9690@electromag.com.au> <7c9dffb7-d55a-98f5-4024-7e2f0c704a56@gmail.com> <7d376874-8078-0252-ed7e-29392a519fc8@gmail.com> From: Jia-Ju Bai Message-ID: <20571ede-a5a2-a901-2e9a-4e78d1520baf@gmail.com> Date: Thu, 12 Apr 2018 09:49:33 +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: <7d376874-8078-0252-ed7e-29392a519fc8@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/4/12 0:19, Florian Fainelli wrote: > On 04/11/2018 12:14 AM, Jia-Ju Bai wrote: >> >> On 2018/4/11 13:30, Phil Reid wrote: >>> 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? >>> >> Yes, I think gpio_set_value_cansleep() is okay here? >> Do I need to send a V2 patch to replace gpio_set_value()? > Yes, I would lump these two changes in the same patch since this is > effectively about solving sleeping vs. non sleeping operations. Okay, I have sent a V2 patch, and you can have a look :) Best wishes, Jia-Ju Bai