From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753775AbeDKQTU (ORCPT ); Wed, 11 Apr 2018 12:19:20 -0400 Received: from mail-qt0-f193.google.com ([209.85.216.193]:43574 "EHLO mail-qt0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753402AbeDKQTR (ORCPT ); Wed, 11 Apr 2018 12:19:17 -0400 X-Google-Smtp-Source: AIpwx492BUpwFVPDipOkpPctCI6yeLIxrpv8IEUj8A8114pmPCr8A/6fZ3buLQvZPQI3eQqvUNjEBw== Subject: Re: [PATCH] net: dsa: b53: Replace mdelay with msleep in b53_switch_reset_gpio To: Jia-Ju Bai , 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> From: Florian Fainelli Openpgp: preference=signencrypt Autocrypt: addr=f.fainelli@gmail.com; prefer-encrypt=mutual; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <7c9dffb7-d55a-98f5-4024-7e2f0c704a56@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Thanks! -- Florian