From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH] RFC: let gpiod_get_optional et all return NULL when GPIOLIB is not enabled Date: Mon, 27 Apr 2015 17:21:53 +0200 Message-ID: <20150427152153.GN19431@pengutronix.de> References: <1423731809-4800-1-git-send-email-u.kleine-koenig@pengutronix.de> <20150306085957.GC10717@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-gpio-owner@vger.kernel.org To: Alexandre Courbot Cc: Linus Walleij , "devicetree@vger.kernel.org" , Grant Likely , Rob Herring , Benjamin Herrenschmidt , Alexandre Courbot , Sascha Hauer , "linux-arm-kernel@lists.infradead.org" , "linux-gpio@vger.kernel.org" List-Id: devicetree@vger.kernel.org Hello, On Thu, Apr 09, 2015 at 11:20:55AM +0900, Alexandre Courbot wrote: > I should have replied one month ago, but if gpiolib is disabled, how > can we use gpiolib-like logic to check the existence of a GPIO? >=20 > Having GPIO disabled means there is no GPIO support, including the > ability to look for GPIOs. -ENOSYS is a well-documented error-code > which meaning also applies to the gpio_*_optional functions (we don't > have support for the operation you requested). If a driver or > architecture really, really needs GPIO support they can require or > depend on CONFIG_GPIOLIB, and the problem goes away. If they can work > with and without gpiolib, then they should check for -ENOSYS when the= y > request GPIOs and behave accordingly. What whould be the right behaviour in your eyes? I hope it's not if (ret !=3D -ENOSYS) return ret; /* continue and ignore error */ > Moving the interpretation of what the absence of gpiolib means down t= o > the GPIO functions themselves is actually what might lead consumers t= o > not know the result of their request. For this reason I would say tha= t > -ENOSYS is appropriate here. Yeah, I fully agree. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= | -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html