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 X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,FAKE_REPLY_C,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B554CC2BB1D for ; Tue, 17 Mar 2020 22:03:40 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7F94F20752 for ; Tue, 17 Mar 2020 22:03:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="RECfhiAM"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="1QGfUU91" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F94F20752 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=haVc2JTaPH1i046N23mKbzg/sP8HcvbK11Enm50aJRE=; b=RECfhiAMQuJE30 4GLHRodP8SLZGolcWTYO7sLNeKoI2BOkiXW/qEnhVH6jYz9LInrScBvlZ5Hru6YLeMbmMk5FOm7wS BSm+/6mopjK2cQExX+oSvHHj0+t6/WvMUM7GGJCahqnjAb8wEH9DM7gffD+E16nfEkBU5vXZIsqoS /c/ALyTNVpFreMPHxp4j7RjFVChej/i+tf3IVXkIJ4mLMq8NpTf5+K80yCAWt2DmtPWYlc23UFTnC obnCZjdZvSMM+bS84UZHBkVVQaB64YiZvRgeBTPWIjLhpGe7305DYjX794/aFOTQP6b+K4wa1w7JR di1HNx1fUyDgf0LpRoag==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jEKJI-0004rg-5F; Tue, 17 Mar 2020 22:03:40 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jEKJF-0004qx-O7; Tue, 17 Mar 2020 22:03:39 +0000 Received: from localhost (mobile-166-175-186-165.mycingular.net [166.175.186.165]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7BC4B20714; Tue, 17 Mar 2020 22:03:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584482616; bh=NRUE2ckhs8n5Ozlq9QGah87GvPHMhCBA9ESXYy5Zdtg=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=1QGfUU91mkGNhqaAE5qkukrE5YGD0RThABDfnFSsg6yyPBnpZ/OoVSS8JJFuWo23r ThYXwUFPgcoopP7DR1QbWF1dlJInVWRqKWlMr64DZHN0CZJTsg5h3FzHB7jeKPHdn0 O36i7OCDqShLa3H4tFGVcqvDcEDogrn3BnfyYFBg= Date: Tue, 17 Mar 2020 17:03:34 -0500 From: Bjorn Helgaas To: Thomas Gleixner Subject: Re: [PATCH 4/5] pci: handled return value of platform_get_irq correctly Message-ID: <20200317220334.GA230141@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200313215642.GA202015@google.com> User-Agent: Mutt/1.12.2 (2019-09-21) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200317_150337_828858_67321306 X-CRM114-Status: GOOD ( 21.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lorenzo Pieralisi , Karthikeyan Mitran , Marc Gonzalez , linux-pci@vger.kernel.org, Linus Walleij , Aman Sharma , linux-kernel@vger.kernel.org, Ryder Lee , linux-mediatek@lists.infradead.org, Thomas Petazzoni , Marc Zyngier , Matthias Brugger , Mans Rullgard , Hou Zhiqiang , linux-arm-kernel@lists.infradead.org, Andrew Murray Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Mar 13, 2020 at 04:56:42PM -0500, Bjorn Helgaas wrote: > On Fri, Mar 13, 2020 at 10:05:58PM +0100, Thomas Gleixner wrote: > > Bjorn Helgaas writes: > > > On Thu, Mar 12, 2020 at 10:53:06AM +0100, Marc Gonzalez wrote: > > >> Last time around, my understanding was that, going forward, > > >> the best solution was: > > >> > > >> virq = platform_get_irq(...) > > >> if (virq <= 0) > > >> return virq ? : -ENODEV; > > >> > > >> i.e. map 0 to -ENODEV, pass other errors as-is, remove the dev_err > > >> > > >> @Bjorn/Lorenzo did you have a change of heart? > > > > > > Yes. In 10006651 (Oct 20, 2017), I thought: > > > > > > irq = platform_get_irq(pdev, 0); > > > if (irq <= 0) > > > return -ENODEV; > > > > > > was fine. In 11066455 (Aug 7, 2019), I said I thought I was wrong and > > > that: > > > > > > platform_get_irq() is a generic interface and we have to be able to > > > interpret return values consistently. The overwhelming consensus > > > among platform_get_irq() callers is to treat "irq < 0" as an error, > > > and I think we should follow suit. > > > ... > > > I think the best pattern is: > > > > > > irq = platform_get_irq(pdev, i); > > > if (irq < 0) > > > return irq; > > > > Careful. 0 is not a valid interrupt. > > Should callers of platform_get_irq() check for a 0 return value? > About 900 of them do not. > > Or should platform_get_irq() return a negative error instead of 0? > If 0 is not a valid interrupt, I think it would be easier to use the > interface if we made it so platform_get_irq() could never return 0, > which I think would also fit the interface documentation better: > > * Return: IRQ number on success, negative error number on failure. Trying again -- I'm not quite catching your meaning, Thomas. If platform_get_irq*() can return 0, but 0 is not a valid IRQ, I think it's sort of complicated to parse that return value. Drivers that require an IRQ would do this: irq = platform_get_irq(pdev, i); if (irq < 0) return irq; if (irq == 0) return -EINVAL; # error since driver requires IRQ return devm_request_irq(dev, irq, ...); Drivers that can either use an IRQ or do polling would do this: irq = platform_get_irq(pdev, i); if (irq <= 0) return setup_polling(); return devm_request_irq(dev, irq, ...); I think those are sort of ungainly, especially the first. If we made it so those functions never returned 0, drivers that need an IRQ could do this: irq = platform_get_irq(pdev, i); if (irq < 0) return irq; return devm_request_irq(dev, irq, ...); and drivers that support polling could do this: irq = platform_get_irq(pdev, i); if (irq < 0) return setup_polling(); return devm_request_irq(dev, irq, ...); That seems a lot easier to get correct, and it matches what most of the callers already do. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel