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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 43B2AC433DF for ; Thu, 20 Aug 2020 16:52:17 +0000 (UTC) Received: from hemlock.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 23A8F207DE for ; Thu, 20 Aug 2020 16:52:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23A8F207DE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 062A78791E; Thu, 20 Aug 2020 16:52:17 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ZKGTfIgUPzMw; Thu, 20 Aug 2020 16:52:16 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id 8B45487824; Thu, 20 Aug 2020 16:52:16 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 824DCC0889; Thu, 20 Aug 2020 16:52:16 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 26D49C0051 for ; Thu, 20 Aug 2020 16:52:16 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 225C88791E for ; Thu, 20 Aug 2020 16:52:16 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JthKybfFmjWX for ; Thu, 20 Aug 2020 16:52:15 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by hemlock.osuosl.org (Postfix) with ESMTPS id 8133487824 for ; Thu, 20 Aug 2020 16:52:15 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 48F9168AFE; Thu, 20 Aug 2020 18:52:13 +0200 (CEST) Date: Thu, 20 Aug 2020 18:52:13 +0200 From: Christoph Hellwig To: Tomasz Figa Subject: Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT Message-ID: <20200820165213.GC12693@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@lst.de> <62e4f4fc-c8a5-3ee8-c576-fe7178cb4356@arm.com> <2b32f1d8-16f7-3352-40a5-420993d52fb5@arm.com> <20200820050214.GA4815@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, Linux Doc Mailing List , nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Christoph Hellwig , linux-samsung-soc , Joonyoung Shim , linux-scsi@vger.kernel.org, "list@263.net:IOMMU DRIVERS" , Ben Skeggs , Matt Porter , Linux Media Mailing List , Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , "list@263.net:IOMMU DRIVERS , Joerg Roedel , " , Thomas Bogendoerfer , linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , Linux Kernel Mailing List , Kyungmin Park , Robin Murphy 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 Thu, Aug 20, 2020 at 12:24:31PM +0200, Tomasz Figa wrote: > > Of course this still uses the scatterlist structure with its annoying > > mix of input and output parametes, so I'd rather not expose it as > > an official API at the DMA layer. > > The problem with the above open coded approach is that it requires > explicit handling of the non-IOMMU and IOMMU cases and this is exactly > what we don't want to have in vb2 and what was actually the job of the > DMA API to hide. Is the plan to actually move the IOMMU handling out > of the DMA API? > > Do you think we could instead turn it into a dma_alloc_noncoherent() > helper, which has similar semantics as dma_alloc_attrs() and handles > the various corner cases (e.g. invalidate_kernel_vmap_range and > flush_kernel_vmap_range) to achieve the desired functionality without > delegating the "hell", as you called it, to the users? Yes, I guess I could do something in that direction. At least for dma-iommu, which thanks to Robin should be all you'll need in the foreseeable future. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu