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 95A5CC41513 for ; Wed, 9 Aug 2023 07:02:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231341AbjHIHCE (ORCPT ); Wed, 9 Aug 2023 03:02:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229468AbjHIHCD (ORCPT ); Wed, 9 Aug 2023 03:02:03 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0696919BC for ; Wed, 9 Aug 2023 00:02:01 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DC73211FB; Wed, 9 Aug 2023 00:02:43 -0700 (PDT) Received: from [10.163.54.83] (unknown [10.163.54.83]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 773AD3F64C; Wed, 9 Aug 2023 00:01:58 -0700 (PDT) Message-ID: Date: Wed, 9 Aug 2023 12:31:56 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH V3 1/4] arm_pmu: acpi: Refactor arm_spe_acpi_register_device() Content-Language: en-US To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, suzuki.poulose@arm.com, Sami Mujawar , Catalin Marinas , Mark Rutland , Mike Leach , Alexander Shishkin , coresight@lists.linaro.org, linux-kernel@vger.kernel.org References: <20230803055652.1322801-1-anshuman.khandual@arm.com> <20230803055652.1322801-2-anshuman.khandual@arm.com> <89058c7c-1fed-60ea-7233-04187772a931@arm.com> <20230804163921.GE30679@willie-the-truck> <9b630f76-2f9e-fc42-012e-403f4b8c1dee@arm.com> <20230808132157.GB2369@willie-the-truck> From: Anshuman Khandual In-Reply-To: <20230808132157.GB2369@willie-the-truck> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/8/23 18:51, Will Deacon wrote: > On Mon, Aug 07, 2023 at 11:03:40AM +0530, Anshuman Khandual wrote: >> On 8/4/23 22:09, Will Deacon wrote: >>> On Thu, Aug 03, 2023 at 11:43:27AM +0530, Anshuman Khandual wrote: >>>> On 8/3/23 11:26, Anshuman Khandual wrote: >>>>> + /* >>>>> + * Sanity check all the GICC tables for the same interrupt >>>>> + * number. For now, only support homogeneous ACPI machines. >>>>> + */ >>>>> + for_each_possible_cpu(cpu) { >>>>> + struct acpi_madt_generic_interrupt *gicc; >>>>> + >>>>> + gicc = acpi_cpu_get_madt_gicc(cpu); >>>>> + if (gicc->header.length < len) >>>>> + return gsi ? -ENXIO : 0; >>>>> + >>>>> + this_gsi = parse_gsi(gicc); >>>>> + if (!this_gsi) >>>>> + return gsi ? -ENXIO : 0; >>>> >>>> Moved parse_gsi() return code checking to its original place just to >>>> make it similar in semantics to existing 'gicc->header.length check'. >>>> If 'gsi' is valid i.e atleast a single cpu has been probed, return >>>> -ENXIO indicating mismatch, otherwise just return 0. >>> >>> Wouldn't that still be the case without the check in this hunk? We'd run >>> into the homogeneous check and return -ENXIO from there, no? >> Although the return code will be the same i.e -ENXIO, but not for the same reason. >> >> this_gsi = parse_gsi(gicc); >> if (!this_gsi) >> return gsi ? -ENXIO : 0; >> >> This returns 0 when IRQ could not be parsed for the first cpu, but returns -ENXIO >> for subsequent cpus. Although return code -ENXIO here still indicates IRQ parsing >> to have failed. >> >> } else if (hetid != this_hetid || gsi != this_gsi) { >> pr_warn("ACPI: %s: must be homogeneous\n", pdev->name); >> return -ENXIO; >> } >> >> This returns -ENXIO when there is a IRQ mismatch. But if the above check is not >> there, -ENXIO return code here could not be classified into IRQ parse problem or >> mismatch without looking into the IRQ value. > > Sorry, but I don't understand your point here. If any of this fails, there's > going to be some debugging needed to look at the ACPI tables; the only > difference with my suggestion is that you'll get a message indicating that > the devices aren't homogeneous, which I think is helpful. I dont have strong opinion either way. Hence will move 'this_gsi' check inside the !gsi conditional check like you had suggested earlier.