From mboxrd@z Thu Jan 1 00:00:00 1970 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2173C433F5 for ; Thu, 18 Nov 2021 21:16:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C90EF61A70 for ; Thu, 18 Nov 2021 21:16:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230023AbhKRVTh (ORCPT ); Thu, 18 Nov 2021 16:19:37 -0500 Received: from mga05.intel.com ([192.55.52.43]:41214 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229521AbhKRVTg (ORCPT ); Thu, 18 Nov 2021 16:19:36 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10172"; a="320508099" X-IronPort-AV: E=Sophos;i="5.87,245,1631602800"; d="scan'208";a="320508099" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Nov 2021 13:16:35 -0800 X-IronPort-AV: E=Sophos;i="5.87,245,1631602800"; d="scan'208";a="587482998" Received: from smile.fi.intel.com ([10.237.72.184]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Nov 2021 13:16:34 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.95) (envelope-from ) id 1mnolg-008Iwg-31; Thu, 18 Nov 2021 23:16:28 +0200 Date: Thu, 18 Nov 2021 23:16:27 +0200 From: Andy Shevchenko To: Bartosz Golaszewski Cc: Linus Walleij , "open list:GPIO SUBSYSTEM" , Linux Kernel Mailing List Subject: Re: [PATCH v2 2/2] gpiolib: check the 'ngpios' property in core gpiolib code Message-ID: References: <20211118132317.15898-1-brgl@bgdev.pl> <20211118132317.15898-2-brgl@bgdev.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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 Thu, Nov 18, 2021 at 09:12:59PM +0100, Bartosz Golaszewski wrote: > On Thu, Nov 18, 2021 at 6:06 PM Andy Shevchenko > wrote: > > On Thu, Nov 18, 2021 at 02:23:17PM +0100, Bartosz Golaszewski wrote: > > > Several drivers read the 'ngpios' device property on their own, but > > > since it's defined as a standard GPIO property in the device tree bindings > > > anyway, it's a good candidate for generalization. If the driver didn't > > > set its gc->ngpio, try to read the 'ngpios' property from the GPIO > > > device's firmware node before bailing out. > > > > ... > > > > > if (gc->ngpio == 0) { > > > - chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > > > - ret = -EINVAL; > > > - goto err_free_descs; > > > + ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); > > > + if (ret) { > > > + chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > > > + ret = -EINVAL; > > > + goto err_free_descs; > > > + } > > > + > > > + gc->ngpio = ngpios; > > > } > > > > This should be > > > > if (gc->ngpio == 0) { > > ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); > > if (ret) > > return ret; > > But device_property_read_u32() returning -ENODATA means there's no > such property, which should actually be converted to -EINVAL as the > caller wanting to create the chip provided invalid configuration - in > this case: a chip with 0 lines. In case of the non-array variant of > read_u32 that's also the only error that can be returned so this bit > looks right to me. So, what is so special about -EINVAL? Why -ENODATA is not good enough which will exactly explain to the caller what's going on, no? > > gc->ngpio = ngpios; > > } > > > > if (gc->ngpio == 0) { > > chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > > ret = -EINVAL; > > goto err_free_descs; When the caller intended to create a chip with 0 GPIOs they will get an error as you wish with an error message. > > } -- With Best Regards, Andy Shevchenko