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_BLOCKED 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 4A5D7C07E95 for ; Fri, 16 Jul 2021 06:26:34 +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 DA189613E7 for ; Fri, 16 Jul 2021 06:26:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DA189613E7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.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 9F94D402CB; Fri, 16 Jul 2021 06:26:33 +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 pEquPvOxfx5q; Fri, 16 Jul 2021 06:26:33 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp2.osuosl.org (Postfix) with ESMTPS id A0C47400D7; Fri, 16 Jul 2021 06:26:32 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 86158C001A; Fri, 16 Jul 2021 06:26:32 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 0A23EC000E for ; Fri, 16 Jul 2021 06:26:31 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id D8D4960C03 for ; Fri, 16 Jul 2021 06:26:30 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp3.osuosl.org (amavisd-new); dkim=pass (2048-bit key) header.d=infradead.org 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 WBBAQfhjS37S for ; Fri, 16 Jul 2021 06:26:30 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by smtp3.osuosl.org (Postfix) with ESMTPS id 3AE146066B for ; Fri, 16 Jul 2021 06:26:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=nUjvHWwQzpb8v3JLLhXC0gHnxeaBdGyJCLTEJYo+tDU=; b=huSKh0okN6XoYJ0y+dNAPgyNBm F7FXsLDRcvDHuySrVPIHVbyStwyItZ/mdSW3L/fqeJJ47c6kBdo/N6Poo2g0iLZB8JaYtHz8Pz2FR aF0dgTJomsYvCIKwL6zIjvxUHCQZVJ8bhRZeAG44PSQ4CKcVEXxGf6aM4lt8rptgyJLFsw3ryiGSE 231k4bokw+Cu6nOyqGfOabFJNNlO6dr/gzmeQIwo5Yqcsx4WM/Nj2H1DHuNNlJVHayhmrjC+8KUyb dstirsS0SKabaihWxuTE6mv8KdQ0UMLkuM7hdYgi4xIsWblap+VguVBQB6wwRahw5mGKn3GUSlZeH 07nz0j9w==; Received: from hch by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m4HGV-004DCm-CL; Fri, 16 Jul 2021 06:24:28 +0000 Date: Fri, 16 Jul 2021 07:24:03 +0100 From: Christoph Hellwig To: Robin Murphy Subject: Re: [PATCH v4 0/3] Apple M1 DART IOMMU driver Message-ID: References: <20210627143405.77298-1-sven@svenpeter.dev> <7261df01-34a9-4e53-37cd-ae1aa15b1fb4@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <7261df01-34a9-4e53-37cd-ae1aa15b1fb4@arm.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Cc: Arnd Bergmann , Mauro Carvalho Chehab , r.czerwinski@pengutronix.de, linux-media@vger.kernel.org, devicetree@vger.kernel.org, Marc Zyngier , Hector Martin , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Rob Herring , Alexander Graf , Alyssa Rosenzweig , Mohamed Mediouni , Mark Kettenis , Will Deacon , linux-arm-kernel@lists.infradead.org, Stan Skowronek 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Wed, Jul 14, 2021 at 07:19:50PM +0100, Robin Murphy wrote: > Even at the DMA API level you could hide *some* of it (at the cost of > effectively only having 1/4 of the usable address space), but there are > still cases like where v4l2 has a hard requirement that a page-aligned > scatterlist can be mapped into a contiguous region of DMA addresses. Where does v4l2 make that broken assumption? Plenty of dma mapping implementations including dma-direct do not support that. Drivers need to call dma_get_merge_boundary() to check for that kind of behavior. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu