Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ABF42C433EF for ; Wed, 12 Jan 2022 12:29:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353169AbiALM3n (ORCPT ); Wed, 12 Jan 2022 07:29:43 -0500 Received: from mga14.intel.com ([192.55.52.115]:52070 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240498AbiALM3e (ORCPT ); Wed, 12 Jan 2022 07:29:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1641990574; x=1673526574; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=7u2c/+u/7900R51hbSn1pNSHHzU5y3Q///2YVkNposY=; b=j3c7xL3T2Cx1Zsd+ppfFG6/CLjSSvIJEAw4QTVLA6tB2AraYJYhd2MhQ ZzwteHKVxIL0j09G0CGrLjs+Yro29FNWzMSWriqRlEDzj0tuAV+6MAFce FxTZzPfLKL4DYBDV/MG/fFU2d3uqphYsKxOsBZpYCZm676LIkOEOk1zA9 GHKd9J8xpYg0QAEoK5ZNSMQlG6vUCblq0FvaR7feDvp7FDMvq+JraGwJw W9CyF2x/uvu0S31lIiDY42CwPpi3G+glyavjQR2Zi03QCWHNKWIQ/lEsp eSrSqKHqfOgdBq6Q9asQ14gg6ZzaY/nwB0wugaZ2F5mzvSs3JUVVIJWL4 Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10224"; a="243922983" X-IronPort-AV: E=Sophos;i="5.88,282,1635231600"; d="scan'208";a="243922983" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jan 2022 04:29:32 -0800 X-IronPort-AV: E=Sophos;i="5.88,282,1635231600"; d="scan'208";a="691367097" Received: from smile.fi.intel.com ([10.237.72.61]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jan 2022 04:29:15 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.95) (envelope-from ) id 1n7cjO-009gDi-VM; Wed, 12 Jan 2022 14:27:58 +0200 Date: Wed, 12 Jan 2022 14:27:58 +0200 From: Andy Shevchenko To: Geert Uytterhoeven Cc: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Andrew Lunn , Ulf Hansson , Vignesh Raghavendra , KVM list , "Rafael J. Wysocki" , linux-iio@vger.kernel.org, Linus Walleij , Amit Kucheria , ALSA Development Mailing List , Liam Girdwood , Guenter Roeck , Thierry Reding , MTD Maling List , Linux I2C , Miquel Raynal , linux-phy@lists.infradead.org, Jiri Slaby , "David S. Miller" , Khuong Dinh , Florian Fainelli , Matthias Schiffer , Joakim Zhang , Kamal Dasu , Lee Jones , Bartosz Golaszewski , Daniel Lezcano , Tony Luck , Kishon Vijay Abraham I , bcm-kernel-feedback-list , "open list:SERIAL DRIVERS" , Jakub Kicinski , Zhang Rui , Matthias Brugger , platform-driver-x86@vger.kernel.org, Linux PWM List , Robert Richter , Saravanan Sekar , Corey Minyard , Linux PM list , Mauro Carvalho Chehab , John Garry , Peter Korsgaard , William Breathitt Gray , Mark Gross , "open list:GPIO SUBSYSTEM" , Alex Williamson , Mark Brown , Borislav Petkov , Eric Auger , Takashi Iwai , Jaroslav Kysela , openipmi-developer@lists.sourceforge.net, Benson Leung , Pengutronix Kernel Team , Linux ARM , linux-edac@vger.kernel.org, Sergey Shtylyov , Richard Weinberger , Mun Yew Tham , Hans de Goede , Greg Kroah-Hartman , Yoshihiro Shimoda , Cornelia Huck , Linux MMC List , Linux Kernel Mailing List , linux-spi , Linux-Renesas , Vinod Koul , James Morse , Zha Qipeng , Sebastian Reichel , Niklas =?iso-8859-1?Q?S=F6derlund?= , linux-mediatek@lists.infradead.org, Brian Norris , netdev@vger.kernel.org Subject: Re: [PATCH 1/2] platform: make platform_get_irq_optional() optional Message-ID: References: <20220110195449.12448-1-s.shtylyov@omp.ru> <20220110195449.12448-2-s.shtylyov@omp.ru> <20220110201014.mtajyrfcfznfhyqm@pengutronix.de> <20220112085009.dbasceh3obfok5dc@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 12, 2022 at 11:27:02AM +0100, Geert Uytterhoeven wrote: > On Wed, Jan 12, 2022 at 9:51 AM Uwe Kleine-K?nig > wrote: > > On Wed, Jan 12, 2022 at 09:33:48AM +0100, Geert Uytterhoeven wrote: > > > On Mon, Jan 10, 2022 at 10:20 PM Andrew Lunn wrote: > > > > On Mon, Jan 10, 2022 at 09:10:14PM +0100, Uwe Kleine-K?nig wrote: > > > > > On Mon, Jan 10, 2022 at 10:54:48PM +0300, Sergey Shtylyov wrote: > > > > > > This patch is based on the former Andy Shevchenko's patch: > > > > > > > > > > > > https://lore.kernel.org/lkml/20210331144526.19439-1-andriy.shevchenko@linux.intel.com/ > > > > > > > > > > > > Currently platform_get_irq_optional() returns an error code even if IRQ > > > > > > resource simply has not been found. It prevents the callers from being > > > > > > error code agnostic in their error handling: > > > > > > > > > > > > ret = platform_get_irq_optional(...); > > > > > > if (ret < 0 && ret != -ENXIO) > > > > > > return ret; // respect deferred probe > > > > > > if (ret > 0) > > > > > > ...we get an IRQ... > > > > > > > > > > > > All other *_optional() APIs seem to return 0 or NULL in case an optional > > > > > > resource is not available. Let's follow this good example, so that the > > > > > > callers would look like: > > > > > > > > > > > > ret = platform_get_irq_optional(...); > > > > > > if (ret < 0) > > > > > > return ret; > > > > > > if (ret > 0) > > > > > > ...we get an IRQ... > > > > > > > > > > The difference to gpiod_get_optional (and most other *_optional) is that > > > > > you can use the NULL value as if it were a valid GPIO. > > > > > > > > > > As this isn't given with for irqs, I don't think changing the return > > > > > value has much sense. > > > > > > > > We actually want platform_get_irq_optional() to look different to all > > > > the other _optional() methods because it is not equivalent. If it > > > > looks the same, developers will assume it is the same, and get > > > > themselves into trouble. > > > > > > Developers already assume it is the same, and thus forget they have > > > to check against -ENXIO instead of zero. > > > > Is this an ack for renaming platform_get_irq_optional() to > > platform_get_irq_silent()? > > No it isn't ;-) > > If an optional IRQ is not present, drivers either just ignore it (e.g. > for devices that can have multiple interrupts or a single muxed IRQ), > or they have to resort to polling. For the latter, fall-back handling > is needed elsewhere in the driver. > To me it sounds much more logical for the driver to check if an > optional irq is non-zero (available) or zero (not available), than to > sprinkle around checks for -ENXIO. In addition, you have to remember > that this one returns -ENXIO, while other APIs use -ENOENT or -ENOSYS > (or some other error code) to indicate absence. I thought not having > to care about the actual error code was the main reason behind the > introduction of the *_optional() APIs. For the record, I'm on the same page with Geert. -- With Best Regards, Andy Shevchenko