From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933411AbcCIRLU (ORCPT ); Wed, 9 Mar 2016 12:11:20 -0500 Received: from avon.wwwdotorg.org ([70.85.31.133]:43710 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751366AbcCIRLP (ORCPT ); Wed, 9 Mar 2016 12:11:15 -0500 Subject: Re: [PATCH 3/5] gpio: of: Return error if gpio hog configuration failed To: Laxman Dewangan References: <1457438528-29054-1-git-send-email-ldewangan@nvidia.com> <1457438528-29054-4-git-send-email-ldewangan@nvidia.com> Cc: linus.walleij@linaro.org, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, treding@nvidia.com, Benoit Parrot , Alexandre Courbot From: Stephen Warren Message-ID: <56E05930.4080805@wwwdotorg.org> Date: Wed, 9 Mar 2016 10:11:12 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <1457438528-29054-4-git-send-email-ldewangan@nvidia.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/08/2016 05:02 AM, Laxman Dewangan wrote: > If GPIO hog configuration failed while adding OF based > gpiochip() then return the error instead of ignoring it. > > This helps of properly handling the gpio driver dependency. > > When adding the gpio hog nodes for NVIDIA's Tegra210 platforms, > the gpio_hogd() fails with EPROBE_DEFER because pinctrl is not > ready at this time and gpio_request() for Tegra GPIO driver > returns error. The error was not causing the Tegra GPIO driver > to fail as the error was getting ignored. > diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c > @@ -218,9 +220,12 @@ static void of_gpiochip_scan_gpios(struct gpio_chip *chip) > if (IS_ERR(desc)) > continue; > > - if (gpiod_hog(desc, name, lflags, dflags)) > - continue; > + ret = gpiod_hog(desc, name, lflags, dflags); > + if (ret < 0) > + return ret; > } > + > + return 0; > } If there are multiple child nodes (which the code above is looping over), and the hog for entries 0, 1, 2 succeed and the hog for entry 3 fails, don't you need to go back and unhog for nodes 0..2 so that the next time this function is called, those hogs won't already be in place thus preventing them from being hogged the second time around? Or does hogging not take ownership of the resource and thus prevent it from being acquired again?