From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751550AbbARL5L (ORCPT ); Sun, 18 Jan 2015 06:57:11 -0500 Received: from metis.ext.pengutronix.de ([92.198.50.35]:59712 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751045AbbARL5I (ORCPT ); Sun, 18 Jan 2015 06:57:08 -0500 Date: Sun, 18 Jan 2015 12:56:51 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Arend van Spriel Cc: Mark Rutland , devicetree@vger.kernel.org, Ian Campbell , Florian Fainelli , Russell King , Pawel Moll , Scott Branden , Wolfram Sang , Ray Jui , Christian Daudt , linux-kernel@vger.kernel.org, Matt Porter , Rob Herring , bcm-kernel-feedback-list@broadcom.com, linux-i2c@vger.kernel.org, Kumar Gala , Grant Likely , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v5 2/3] i2c: iproc: Add Broadcom iProc I2C Driver Message-ID: <20150118115650.GH22880@pengutronix.de> References: <1421451737-7107-1-git-send-email-rjui@broadcom.com> <1421451737-7107-3-git-send-email-rjui@broadcom.com> <54BB795C.6040402@broadcom.com> <20150118094741.GE22880@pengutronix.de> <20150118110658.GA1113@katana> <20150118111759.GG22880@pengutronix.de> <54BB9D2B.20408@broadcom.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <54BB9D2B.20408@broadcom.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Sun, Jan 18, 2015 at 12:46:51PM +0100, Arend van Spriel wrote: > On 01/18/15 12:17, Uwe Kleine-König wrote: > >Hello Wolfram, > > > >On Sun, Jan 18, 2015 at 12:06:58PM +0100, Wolfram Sang wrote: > >>On Sun, Jan 18, 2015 at 10:47:41AM +0100, Uwe Kleine-König wrote: > >>>On Sun, Jan 18, 2015 at 10:14:04AM +0100, Arend van Spriel wrote: > >>>>On 01/17/15 00:42, Ray Jui wrote: > >>>>>+ complete_all(&iproc_i2c->done); > >>>> > >>>>Looking over this code it seems to me there is always a single > >>>>process waiting for iproc_i2c->done to complete. So using complete() > >>>>here would suffice. > >>>Yeah, there is always only a single thread waiting. That means both > >>>complete and complete_all are suitable. AFAIK there is no reason to pick > >>>one over the other in this case. > >> > >>Clarity? > >And which do you consider more clear? complete_all might result in the > >question: "Is there>1 waiter?" and complete might yield to "What about > >the other waiters?". If you already know there is only one, both are on > >par on clarity. Might only be me?! I don't care much. > > Maybe it is me, but it is not about questions but it is about > implicit statements that the code makes (or reader derives from it). > When using complete_all you indicate to the reader "there can be > more than one waiter". When using complete it indicates "there is > only one waiter". If those statements are not true that is a code No, complete works just fine in the presence of >1 waiter. It just wakes a single waiter and all others continue to wait. That is, for single-waiter situations there is no semantic difference between complete and complete_all. But there is a difference for multi-waiter queues. I think this is just a matter of your POV in the single-waiter situation: complete might be intuitive because you just completed a single task and complete_all might be intuitive because it signals "I'm completely done, there is noone waiting for me any more.". Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |