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 48904EB64DD for ; Wed, 12 Jul 2023 16:26:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232082AbjGLQ0C (ORCPT ); Wed, 12 Jul 2023 12:26:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231593AbjGLQZe (ORCPT ); Wed, 12 Jul 2023 12:25:34 -0400 Received: from mx01.omp.ru (mx01.omp.ru [90.154.21.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1BAE21BFA; Wed, 12 Jul 2023 09:25:33 -0700 (PDT) Received: from [192.168.1.103] (178.176.76.110) by msexch01.omp.ru (10.188.4.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.986.14; Wed, 12 Jul 2023 19:25:25 +0300 Subject: Re: [PATCH] sh: Avoid using IRQ0 on SH3 and SH4 To: Guenter Roeck , Sergei Shtylyov , David Laight , 'John Paul Adrian Glaubitz' , Geert Uytterhoeven CC: Yoshinori Sato , Rich Felker , "linux-sh@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <7b2c0d812280afaefee0c70a9aea00a0fcf84e3a.camel@physik.fu-berlin.de> <1178f8d0-be70-c088-ee6a-8b421b290624@roeck-us.net> From: Sergey Shtylyov Organization: Open Mobile Platform Message-ID: <463596f8-e3d7-923a-6003-7b693f11b904@omp.ru> Date: Wed, 12 Jul 2023 19:25:24 +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: 8bit X-Originating-IP: [178.176.76.110] X-ClientProxiedBy: msexch01.omp.ru (10.188.4.12) To msexch01.omp.ru (10.188.4.12) X-KSE-ServerInfo: msexch01.omp.ru, 9 X-KSE-AntiSpam-Interceptor-Info: scan successful X-KSE-AntiSpam-Version: 5.9.59, Database issued on: 07/12/2023 16:08:17 X-KSE-AntiSpam-Status: KAS_STATUS_NOT_DETECTED X-KSE-AntiSpam-Method: none X-KSE-AntiSpam-Rate: 59 X-KSE-AntiSpam-Info: Lua profiles 178587 [Jul 12 2023] X-KSE-AntiSpam-Info: Version: 5.9.59.0 X-KSE-AntiSpam-Info: Envelope from: s.shtylyov@omp.ru X-KSE-AntiSpam-Info: LuaCore: 521 521 0c3391dd6036774f2e1052158c81e48587b96e95 X-KSE-AntiSpam-Info: {rep_avail} X-KSE-AntiSpam-Info: {Tracking_uf_ne_domains} X-KSE-AntiSpam-Info: {Tracking_from_domain_doesnt_match_to} X-KSE-AntiSpam-Info: {relay has no DNS name} X-KSE-AntiSpam-Info: {SMTP from is not routable} X-KSE-AntiSpam-Info: {Found in DNSBL: 178.176.76.110 in (user) b.barracudacentral.org} X-KSE-AntiSpam-Info: {Found in DNSBL: 178.176.76.110 in (user) dbl.spamhaus.org} X-KSE-AntiSpam-Info: git.kernel.org:7.1.1;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1;omp.ru:7.1.1;127.0.0.199:7.1.2 X-KSE-AntiSpam-Info: ApMailHostAddress: 178.176.76.110 X-KSE-AntiSpam-Info: {DNS response errors} X-KSE-AntiSpam-Info: Rate: 59 X-KSE-AntiSpam-Info: Status: not_detected X-KSE-AntiSpam-Info: Method: none X-KSE-AntiSpam-Info: Auth:dmarc=temperror header.from=omp.ru;spf=temperror smtp.mailfrom=omp.ru;dkim=none X-KSE-Antiphishing-Info: Clean X-KSE-Antiphishing-ScanningType: Heuristic X-KSE-Antiphishing-Method: None X-KSE-Antiphishing-Bases: 07/12/2023 16:15:00 X-KSE-Antivirus-Interceptor-Info: scan successful X-KSE-Antivirus-Info: Clean, bases: 7/12/2023 2:02:00 PM X-KSE-Attachment-Filter-Triggered-Rules: Clean X-KSE-Attachment-Filter-Triggered-Filters: Clean X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/12/23 7:22 PM, Sergey Shtylyov wrote: > [...] > >>>>> Sent: 09 July 2023 00:13 >>>> .... >>>>> Looking at arch/sh/boards/mach-r2d/irq.c, there is some IRQ translation going >>>>> on and maybe that's the part where we need to correct the offset by 16? >>>> >>>> Would it be less problematic to use (say) 16 for IRQ_0 >>>> leaving IRQ_1+ as 1+ ? >>> >>>     I don't think so. >>> >>>> At least that would only cause issues for code that needed >>>> to use IRQ_0. >>>> >>>> (It has to be said that making IRQ 0 invalid seemed wrong >>>> to me. x86 (IBM PC) gets away with it because IRQ 0 is >>>> always assigned to platform specific hardware.) >>> >>>     Not only x86, IIRC. >>>     Have you seen the commit below? >>> >>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ce753ad1549cbe9ccaea4c06a1f5fa47432c8289 >>> >> >> Quoting: >> >> using IRQ0 is considered invalid (according to Linus) outside the arch/ code >>                                                       ^^^^^^^^^^^^^^^^^^^^^^> The changes here were made _in_ the arch code. While there may be valid >> arguments for doing that, quoting the above commit as reason isn't really >> sufficient. > > It seems you still don't understand... The i8253 drivers using IRQ0 live in > the arch/{mips|x86}/kernel/ code, so they're allowed to claim IRQ0 via calling > request_irq() (MIPS still does it. x86 too. PowerPC used to do that too, IIRC... >> They are NOT the platform drivers we're dealing with here... >> Guenter MBR, Sergey