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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3C63C433F5 for ; Mon, 13 Dec 2021 11:53:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234461AbhLMLxT (ORCPT ); Mon, 13 Dec 2021 06:53:19 -0500 Received: from mga09.intel.com ([134.134.136.24]:19391 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229618AbhLMLxS (ORCPT ); Mon, 13 Dec 2021 06:53:18 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10196"; a="238532082" X-IronPort-AV: E=Sophos;i="5.88,202,1635231600"; d="scan'208";a="238532082" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Dec 2021 03:53:18 -0800 X-IronPort-AV: E=Sophos;i="5.88,202,1635231600"; d="scan'208";a="464600657" Received: from smile.fi.intel.com ([10.237.72.184]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Dec 2021 03:53:16 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.95) (envelope-from ) id 1mwjsR-005bR7-V5; Mon, 13 Dec 2021 13:52:19 +0200 Date: Mon, 13 Dec 2021 13:52:19 +0200 From: Andy Shevchenko To: Damien Le Moal Cc: Sergey Shtylyov , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, Hans de Goede , Jens Axboe Subject: Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved Message-ID: References: <20211209145937.77719-1-andriy.shevchenko@linux.intel.com> <549c1825-56e6-de9e-e109-77f0d06cfd0f@opensource.wdc.com> <5322dafd-86ad-a293-6005-29384cb96cc8@omp.ru> 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 Mon, Dec 13, 2021 at 07:39:31AM +0900, Damien Le Moal wrote: > On 2021/12/11 19:25, Sergey Shtylyov wrote: > > On 11.12.2021 2:45, Damien Le Moal wrote: ... > >>>> So 0 will be returned as-is. That is rather weird. That should be fixed to > >>>> return -ENXIO: > >>>> > >>>> if (WARN(ret == 0, "0 is an invalid IRQ number\n")) > >>>> return -ENXIO; > >>>> return ret; > >>> > >>> My unmerged patch (https://marc.info/?l=linux-kernel&m=163623041902285) does this > >>> but returns -EINVAL instead. > >> > >> Thinking more about this, shouldn't this change go into platform_get_irq() > >> instead of platform_get_irq_optional() ? > > > > Why? platform_get_irq() currently just calls platform_get_irq_optional()... > > > >> The way I see it, I think that the intended behavior for > >> platform_get_irq_optional() is: > >> 1) If have IRQ, return it, always > 0 > >> 2) If no IRQ, return 0 > > > > That does include the IRQ0 case, right? > > IRQ 0 being invalid, I think that case should be dealt with internally within > platform_get_irq_optional() and warn/error return. IRQ 0 showing up would thus > be case (3), an error. > > > > >> 3) If error, return < 0 > >> no ? > > > > I completely agree, I (after thinking a bit) have no issues with that... > > > >> And for platform_get_irq(), case (2) becomes an error. > >> Is this the intended semantic ? > > > > I don't see how it's different from the current behavior. But we can do > > that as well, I just don't see whether it's really better... > > The problem I see is that the current behavior is unclear: what does > platform_get_irq_optional() returning 0 mean ? IRQ == 0 ? or "no IRQ" ? I think > it should be the latter rather than the former. Note that the function could > return ENOENT (or similar) for the "no IRQ" case. With that, case (2) goes away, > but then I do not see any difference between platform_get_irq_optional() and > platform_get_irq(). > > If the preferred API semantic is to allow returning IRQ 0 with a warning, then > the kdoc comments of platform_get_irq_optional() and platform_get_irq() are > totally broken, and the code for many drivers is probably wrong too. Yeah, what we need to do is that (roughly a roadmap): - revisit callers of platform_get_irq_optional() to be prepared for new behaviour - rewrite platform_get_irq() to return -ENOENT - rewrite platform_get_irq_optional() to return 0 on -ENOENT This is how other similar (i.e. _optional) APIs do. -- With Best Regards, Andy Shevchenko