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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_RED 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 12C1EC433C1 for ; Sat, 27 Mar 2021 15:34:21 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 931666192B for ; Sat, 27 Mar 2021 15:34:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 931666192B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lists.linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 5C4B34019B; Sat, 27 Mar 2021 15:34:20 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BdCfpuUrHe7o; Sat, 27 Mar 2021 15:34:19 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp2.osuosl.org (Postfix) with ESMTP id DC2FE40139; Sat, 27 Mar 2021 15:34:18 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id B549CC000B; Sat, 27 Mar 2021 15:34:18 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [IPv6:2605:bc80:3010::136]) by lists.linuxfoundation.org (Postfix) with ESMTP id CF2F1C000A for ; Sat, 27 Mar 2021 15:34:17 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id AC27A605FF for ; Sat, 27 Mar 2021 15:34:17 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp3.osuosl.org (amavisd-new); dkim=pass (2048-bit key) header.d=svenpeter.dev header.b="cejNuovT"; dkim=pass (2048-bit key) header.d=messagingengine.com header.b="KSStNAPR" Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id gg6EdmXN8Ijh for ; Sat, 27 Mar 2021 15:34:15 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from new4-smtp.messagingengine.com (new4-smtp.messagingengine.com [66.111.4.230]) by smtp3.osuosl.org (Postfix) with ESMTPS id C0B83605BC for ; Sat, 27 Mar 2021 15:34:14 +0000 (UTC) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailnew.nyi.internal (Postfix) with ESMTP id 67F1258055A; Sat, 27 Mar 2021 11:34:12 -0400 (EDT) Received: from imap21 ([10.202.2.71]) by compute3.internal (MEProxy); Sat, 27 Mar 2021 11:34:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=svenpeter.dev; h=mime-version:message-id:in-reply-to:references:date:from:to :cc:subject:content-type; s=fm1; bh=C7jUmzBlfmU9VFdYvmkyNor1Zqsj 5fCr/9TW5SN6eG4=; b=cejNuovTAzdGTboZGSEobUwyj2OEBYn4LYOBN+UDnLmH f55CfBtYftdhKeCuZ+MGt8o7smZ0EaSsAfy9iVYge7EJ2AbYWRo1xUnr41Bsj5WC JfWy44cCOpuaKx9B37gWO3zrJa8jVeRXYWbzNs8k3Yqk+49lM5BhCWgHc6rnpnO7 3wttehSaRphhIJ091wvtCkbu7dF8xxNryyGWIQzkq8y5wRdeQqep4R6dVRt33gCQ w3HIl+vARuRnFz9mUMMKR66Kfo1No4Szo0sW2mPFQa0kAmh74tIPEi3kNSHbEUX8 MkGRf++HdPhPu6V7OjWwMP6vxHsLoyVuVe6ZUNfvdg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=C7jUmz BlfmU9VFdYvmkyNor1Zqsj5fCr/9TW5SN6eG4=; b=KSStNAPRTX4FY94hwirZH5 NtxQPIDTc2Tgq/dWZS3eABO/xJiFidm9zflpeUlb6i3Q6DAwnXeIYyVRqx1AcKLS 1qz7rYzsaNhX+T//2nR9xIwnQM9K0NNPkBSEQIS+phXRVysFUK3lhqaps3z3lHrE F+9rTCBH0TKNRbHB5Y6roDui4sL0VdPnYuaQBSIYPO83epf8r2kGsg9eOp7b8JZa F0+XDu/dxfdZQvTO7HCp/wTbXjZEnAZhte+dAi6doLS88uyE8twBdGVHcyZBHGPg dpQ/9Y21a3E7TS2fZ4SJqnuOW5Z0qzShqpqbIu+WsrMMqxluMExX9TqFQwdfhPHQ == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrudehgedgjeekucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepofgfggfkjghffffhvffutgesthdtredtreertdenucfhrhhomhepfdfuvhgv nhcurfgvthgvrhdfuceoshhvvghnsehsvhgvnhhpvghtvghrrdguvghvqeenucggtffrrg htthgvrhhnpefgieegieffuefhtedtjefgteejteefleefgfefgfdvvddtgffhffduhedv feekffenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe hsvhgvnhesshhvvghnphgvthgvrhdruggvvh X-ME-Proxy: Received: by mailuser.nyi.internal (Postfix, from userid 501) id 6169E51C005E; Sat, 27 Mar 2021 11:34:10 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.5.0-alpha0-273-g8500d2492d-fm-20210323.002-g8500d249 Mime-Version: 1.0 Message-Id: <26c9b3cc-a04f-444d-ada4-0c9bc99684e5@www.fastmail.com> In-Reply-To: <33b3ce35-c42f-331a-79a2-e38917d588ef@arm.com> References: <20210320151903.60759-1-sven@svenpeter.dev> <20210323205346.GA1283560@robh.at.kernel.org> <43685c67-6d9c-4e72-b320-0462c2273bf0@www.fastmail.com> <33b3ce35-c42f-331a-79a2-e38917d588ef@arm.com> Date: Sat, 27 Mar 2021 16:33:29 +0100 To: "Robin Murphy" , "Rob Herring" , "Mark Kettenis" Subject: Re: [PATCH 0/3] Apple M1 DART IOMMU driver Cc: Arnd Bergmann , devicetree@vger.kernel.org, Marc Zyngier , Hector Martin , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, mohamed.mediouni@caramail.com, Will Deacon , linux-arm-kernel@lists.infradead.org, stan@corellium.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Sven Peter via iommu Reply-To: Sven Peter Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi Robin, On Thu, Mar 25, 2021, at 12:50, Robin Murphy wrote: > On 2021-03-25 07:53, Sven Peter wrote: > > The iommu binding documentation [1] mentions that > > > > The device tree node of the IOMMU device's parent bus must contain a valid > > "dma-ranges" property that describes how the physical address space of the > > IOMMU maps to memory. An empty "dma-ranges" property means that there is a > > 1:1 mapping from IOMMU to memory. > > > > which, if I understand this correctly, means that the 'dma-ranges' for the > > parent bus of the iommu should be empty since the DART hardware can see the > > full physical address space with a 1:1 mapping. > > > > > > The documentation also mentions that > > > > When an "iommus" property is specified in a device tree node, the IOMMU > > will be used for address translation. If a "dma-ranges" property exists > > in the device's parent node it will be ignored. > > > > which means that specifying a 'dma-ranges' in the parent bus of any devices > > that use the iommu will just be ignored. > > I think that's just wrong and wants updating (or at least clarifying). > The high-level view now is that we use "dma-ranges" to describe > limitations imposed by a bridge or interconnect segment, and that can > certainly happen upstream of an IOMMU. As it happens, I've just recently > sent a patch for precisely that case[1]. > > I guess what it might have been trying to say is that "dma-ranges" > *does* become irrelevant in terms of constraining what physical memory > is usable for DMA, but that shouldn't imply that its meaning doesn't > just shift to a different purpose. Should I add a patch to clarify this paragraph for v2 or submit a separate one-off patch? I'm not entirely sure about the process here but I could add a Suggested-by: to the commit if that's fine with you. Best, Sven _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu