From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5870731A82 for ; Tue, 3 Oct 2023 16:19:06 +0000 (UTC) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 59824BF; Tue, 3 Oct 2023 09:19:05 -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 AE6C0C15; Tue, 3 Oct 2023 09:19:43 -0700 (PDT) Received: from [10.1.196.40] (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2A5393F762; Tue, 3 Oct 2023 09:19:04 -0700 (PDT) Message-ID: Date: Tue, 3 Oct 2023 17:18:55 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH 2/2] irqchip/gic-v3: Enable non-coherent redistributors/ITSes probing Content-Language: en-GB To: Lorenzo Pieralisi , Marc Zyngier Cc: linux-kernel@vger.kernel.org, Mark Rutland , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, Rob Herring , Fang Xiang References: <20230905104721.52199-1-lpieralisi@kernel.org> <20230905104721.52199-3-lpieralisi@kernel.org> <86msy0etul.wl-maz@kernel.org> From: Robin Murphy In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-5.3 required=5.0 tests=BAYES_00,NICE_REPLY_A, RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On 03/10/2023 3:43 pm, Lorenzo Pieralisi wrote: > On Tue, Sep 05, 2023 at 12:34:58PM +0100, Marc Zyngier wrote: > > [...] > >>> * Make sure *all* the ITS are reset before we probe any, as >>> * they may be sharing memory. If any of the ITS fails to >>> @@ -5396,7 +5405,8 @@ static int __init its_of_probe(struct device_node *node) >>> continue; >>> } >>> >>> - its_probe_one(&res, &np->fwnode, of_node_to_nid(np)); >>> + its_probe_one(&res, &np->fwnode, of_node_to_nid(np), >>> + of_property_read_bool(np, "dma-noncoherent")); >>> } >>> return 0; >>> } >>> @@ -5533,7 +5543,8 @@ static int __init gic_acpi_parse_madt_its(union acpi_subtable_headers *header, >>> } >>> >>> err = its_probe_one(&res, dom_handle, >>> - acpi_get_its_numa_node(its_entry->translation_id)); >>> + acpi_get_its_numa_node(its_entry->translation_id), >>> + false); >> >> I came up with the following alternative approach, which is as usual >> completely untested. It is entirely based on the quirk infrastructure, >> and doesn't touch the ACPI path at all. > > Writing the ACPI bits. We can't use the quirks framework for ACPI (we > don't have "properties" and I don't think we want to attach any to the > fwnode_handle) that's why I generalized its_probe_one() above with an > extra param, that would have simplified ACPI parsing: > > - we alloc struct its_node in its_probe_one() but at that stage > ACPI parsing was already done. If we have to parse the MADT(ITS) again > just to scan for non-coherent we then have to match the MADT entries > to the *current* struct its_node* we are handling (MADT parsing > callbacks don't even take a param - we have to resort to global > variables - definitely doable but it is a bit ugly). How about a compromise of passing a whole MADT flags field into its_probe_one() (where its_of_probe() can just pass 0), to pass through to its_enable_quirks() to then match against an madt_flags field in the gic_quirk? gic_acpi_init() could then do something similar for the redistributor quirk, although I guess it would then need to distinguish GICC and GICR-based quirks cases since the respective flags are in different formats. Thanks, Robin.