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 D1426C433FE for ; Fri, 10 Dec 2021 17:39:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241886AbhLJRnS (ORCPT ); Fri, 10 Dec 2021 12:43:18 -0500 Received: from mxout04.lancloud.ru ([45.84.86.114]:54666 "EHLO mxout04.lancloud.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231337AbhLJRnR (ORCPT ); Fri, 10 Dec 2021 12:43:17 -0500 Received: from LanCloud DKIM-Filter: OpenDKIM Filter v2.11.0 mxout04.lancloud.ru E917820A2A41 Received: from LanCloud Received: from LanCloud Received: from LanCloud Subject: Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved To: Andy Shevchenko CC: , , Hans de Goede , Jens Axboe , Damien Le Moal References: <20211209145937.77719-1-andriy.shevchenko@linux.intel.com> <15cf03b2-8d45-93b1-f0a0-d79c93cee0da@omp.ru> <7ffe328f-2ba1-4799-5c6a-d48d88c0459d@omp.ru> From: Sergey Shtylyov Organization: Open Mobile Platform Message-ID: <51c0aa6e-e75f-faa7-b9b1-850684da58c8@omp.ru> Date: Fri, 10 Dec 2021 20:39:38 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.11.198] X-ClientProxiedBy: LFEXT01.lancloud.ru (fd00:f066::141) To LFEX1907.lancloud.ru (fd00:f066::207) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/10/21 2:28 PM, Andy Shevchenko wrote: >>>>>>>>> While at it, drop redundant check for 0 as platform_get_irq() spills >>>>>>>>> out a big WARN() in such case. >>>>>>>> >>>>>>>> And? IRQ0 is still returned! :-( >>>>>>> >>>>>>> It should not be returned in the first place. >>>>>> >>>>>> But it still is, despite the WARN(), right? >>>>> >>>>> So, you admit that there is a code which does that? >>>> >>>> I admit *what*?! That platfrom_get_irq() and its ilk return IRQ0 while they >>>> shouldn't? =) >>> >>> That there is a code beneath platform_get_irq() that returns 0, yes. >> >> Look at the ACPI-specific GpioInt handling code (just above the out_not_found label) -- >> I'm not sure the check there is correct -- I'm not very familiar with ACPI, you seem to >> know it much better. :-) > > And what is your point here exactly? You're saying IRQ0 shouldn't be returned (by the ACPI code) -- from this fragment we can see that it may be returned... > If == 0 case happens, it will be > immediately WARN() and reported (I hope) Well, "hope dies last"... :-) > since it will mean bug in the code. > >> Also, 0 can be specified via the normal IRQ resource. I know of e.g. the Alchemy MIPS SoCs >> that have IRQ0 used by UART0; luckily, currently SoC IRQs are mapped starting at Linux IRQ8 >> (but it wasn't the case in the 2.6.1x time frame where we had issue with the serial driver)... > > You mixed up HW IRQ with vIRQ. I didn't. Linux expects the vIRQs (I called them Linux IRQs). In the 2.6.1x time frame those corresponded 1:1 on Alchemy. Also, there's 8259 which is always mapped at vIRQ0 (or the legacy drivers won't work). > The former one may be 0 and it's completely valid case, while > the second one is not. Well, request_irq() happilly takes vIRQ0. Moreover, there are 8253 drivers in e.g. the arch/x86/ (PPC and MIPS too) which do use vIRQ0. >>>>> That code should be fixed first. Have you sent a patch? >>>> >>>> Which code?! You got me totally muddled. =) >>> >>> Above mentioned. >> >> What needs to be fixed in this case is the interrupt controller driver. > > What do you mean by that? You better ask Linus... ;-) > vIRQ is handled by IRQ core, IRQ controller driver > just a mere provider of the resource. And those exceptions for vIRQ == 0 > shouldn't be propagated to the platform code or so. >> Quoting Linus >> (imprecisely :-)), IRQ #s should be either mapped starting with #1 or IRQ0 remapped at >> the end of the controller's interrupt range... I currently have no information on the >> platforms requiring such kind of fixing (Alchemy don't seem to need it now)... Well, actually that Linus' quote predates drivers/irqchip/, so I must confess this argument was wrong... :-) > Again, do not mix vIRQ (about which Linus ranted) and HW IRQ. > > ... > >>>>>>>>> - if (!irq) >>>>>>>>> - return -EINVAL; >>>>>>>> >>>>>>>> This is prermature -- let's wait till my patch that stops returning IRQ0 from >>>>>>>> platform_get_irq() and friends gets merged.... >>>>>>> >>>>>>> What patch? >>>>>> >>>>>> https://marc.info/?l=linux-kernel&m=163623041902285 >>>>>> >>>>>>> Does it fix platform_get_irq_optional()? >>>>>> >>>>>> Of course! :-) >>>>> >>>>> Can you share link to lore.kernel.org, please? >>>>> It will make much easier to try and comment. >>>> >>>> I don't know how to uise it yet, and I'm a little busy with other IRQ0 issues ATM, > >> A little bit, I meant to type. > > No problem. I just haven't got what other IRQ0 issues except fixing > platform_get_irq_optional() et al. could be possibly needed... There is other IRQ0 issue which is very old already... [...] MBR, Sergey