From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753430AbeAZQ1A (ORCPT ); Fri, 26 Jan 2018 11:27:00 -0500 Received: from mail-oi0-f66.google.com ([209.85.218.66]:42990 "EHLO mail-oi0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753007AbeAZQ0b (ORCPT ); Fri, 26 Jan 2018 11:26:31 -0500 X-Google-Smtp-Source: AH8x225fYK30Iy9mzdy3GV0LVe6CGi5jX81WHX78Nj3hmdVn7O2Vojbdz30sqbYxCD2MzSCDJ0B7dQ== Subject: Re: [PATCH] bcma: Replace mdelay with usleep_range in bcma_pmu_resources_init To: Jia-Ju Bai , zajec5@gmail.com, hauke@hauke-m.de Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org References: <1516958011-303-1-git-send-email-baijiaju1990@gmail.com> From: Larry Finger Message-ID: Date: Fri, 26 Jan 2018 10:26:29 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <1516958011-303-1-git-send-email-baijiaju1990@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/26/2018 03:13 AM, Jia-Ju Bai wrote: > After checking all possible call chains to bcma_pmu_resources_init() here, > my tool finds that this function is never called in atomic context, > namely never in an interrupt handler or holding a spinlock. > Thus mdelay can be replaced with usleep_range to avoid busy wait. > > This is found by a static analysis tool named DCNS written by myself. > > Signed-off-by: Jia-Ju Bai > --- > drivers/bcma/driver_chipcommon_pmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/bcma/driver_chipcommon_pmu.c b/drivers/bcma/driver_chipcommon_pmu.c > index f1eb4d3..478948c 100644 > --- a/drivers/bcma/driver_chipcommon_pmu.c > +++ b/drivers/bcma/driver_chipcommon_pmu.c > @@ -203,7 +203,7 @@ static void bcma_pmu_resources_init(struct bcma_drv_cc *cc) > * Add some delay; allow resources to come up and settle. > * Delay is required for SoC (early init). > */ > - mdelay(2); > + usleep_range(1500, 2000); I have no idea how critical this delay might be, but it would be safer to never make the sleep be shorter than the original delay. Using (2000, 2500) would be a better choice of arguments for usleep_range(). NACK Larry