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=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 79E54C3712F for ; Mon, 21 Jan 2019 21:30:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 38A1020861 for ; Mon, 21 Jan 2019 21:30:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="MRFxsVSt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728014AbfAUVac (ORCPT ); Mon, 21 Jan 2019 16:30:32 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:55174 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727605AbfAUVac (ORCPT ); Mon, 21 Jan 2019 16:30:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=IDcb7s4cNraG/2a1cXf3u05xgct90adkEl26XoaC8RY=; b=MRFxsVStKsekj4UYcs0XPLSpx bSj7Ak2pDhMBrwVMo5FXRWO6rvWvKdTuzFTNnhR4ez40SnpfDuY0jmU5zztKhBVfjtWbVvEiYY4g0 RUvOgGtt8ZPjtJrVSkgvJOKe9En8oXFp4OlIiES6R8cAfSeigME/YYLvFChNqYD+Y4r2YytEdTYqT XpB0UxG1qjvpQrWER4N5v6SfzqTz1jx1IPMjiorDIQoDewUH4bJli/Cc6S2q8OQOWoPnOx3Xd2ryt g5Q6MJeT1NBICzaN5m+6TwRfV2aMMPUY4hQVFLz2YkDJ/lA+aQJnhQNwa/aJc9rRaubLqfegpLzAX ArZ+TudDQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1glh9I-0000Ls-Lu; Mon, 21 Jan 2019 21:30:28 +0000 Date: Mon, 21 Jan 2019 13:30:28 -0800 From: Christoph Hellwig To: Liam Mark Cc: "Andrew F. Davis" , Christoph Hellwig , Laura Abbott , sumit.semwal@linaro.org, arve@android.com, tkjos@android.com, maco@android.com, joel@joelfernandes.org, christian@brauner.io, devel@driverdev.osuosl.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, john.stultz@linaro.org Subject: Re: [PATCH 3/4] dma-buf: add support for mapping with dma mapping attributes Message-ID: <20190121213028.GB28620@infradead.org> References: <1547836667-13695-1-git-send-email-lmark@codeaurora.org> <1547836667-13695-4-git-send-email-lmark@codeaurora.org> <20190119102527.GA17723@infradead.org> <7ae73c39-9049-bcf6-775f-b0817ba0ec5f@redhat.com> <20190121083046.GD12420@infradead.org> <0ed7875f-15e9-184f-5b99-9a53df7c8d14@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 21, 2019 at 12:20:42PM -0800, Liam Mark wrote: > I have left this to clients, but if they own the buffer they can have the > knowledge as to whether CPU access is needed in that use case (example for > post-processing). That is an API design which the user is more likely to get wrong than right and thus does not pass the smell test.