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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 4B398CA9ED1 for ; Fri, 1 Nov 2019 12:28:34 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 1BD7B217D9 for ; Fri, 1 Nov 2019 12:28:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1BD7B217D9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id ADFC014D1; Fri, 1 Nov 2019 12:28:33 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 45D8A14A1 for ; Fri, 1 Nov 2019 12:28:32 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id C96AF63D for ; Fri, 1 Nov 2019 12:28:31 +0000 (UTC) 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 27DFB1F1; Fri, 1 Nov 2019 05:28:31 -0700 (PDT) Received: from e121166-lin.cambridge.arm.com (e121166-lin.cambridge.arm.com [10.1.196.255]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 22B613F6C4; Fri, 1 Nov 2019 05:28:30 -0700 (PDT) Date: Fri, 1 Nov 2019 12:28:25 +0000 From: Lorenzo Pieralisi To: Jean-Philippe Brucker Subject: Re: [PATCH 0/7] iommu: Permit modular builds of ARM SMMU[v3] drivers Message-ID: <20191101122825.GA318@e121166-lin.cambridge.arm.com> References: <20191030145112.19738-1-will@kernel.org> <6e457227-ca06-2998-4ffa-a58ab171ce32@arm.com> <20191030155444.GC19096@willie-the-truck> <20191031193758.GA2607492@lophozonia> <20191101114148.GA2694906@lophozonia> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191101114148.GA2694906@lophozonia> User-Agent: Mutt/1.9.4 (2018-02-28) Cc: Saravana Kannan , Will Deacon , LKML , iommu@lists.linux-foundation.org, Bjorn Helgaas , Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Fri, Nov 01, 2019 at 12:41:48PM +0100, Jean-Philippe Brucker wrote: [...] > > > I'm also wondering about ACPI support. > > > > I'd love to add ACPI support too, but I have zero knowledge of ACPI. > > I'd be happy to help anyone who wants to add ACPI support that allows > > ACPI to add device links. > > It's not as generic as device-tree, each vendor has their own table to > describe the IOMMU topology. I don't see a nice way to transpose the > add_links() callback there. Links need to be created either in a common > path (iommu_probe_device()) or in the APCI IORT driver. We can create a generic stub that calls into respective firmware handling paths (eg iort_dma_setup() in acpi_dma_configure()). There are three arches booting with ACPI so stubbing it out in specific firmware handlers is not such a big deal, less generic sure, but not catastrophically bad. Obviously this works for IOMMU masters links - for resources dependencies (eg power domains) it deserves some thought, keeping in mind that IOMMUs are static table entries in ACPI and not device objects so they are not even capable of expressing eg power resources and suchlike. Long story short: adding IOMMU masters links in ACPI should be reasonably simple, everything else requires further thought. Lorenzo _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu