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_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,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 59F5DC48BD4 for ; Tue, 25 Jun 2019 06:14:15 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 309BD20652 for ; Tue, 25 Jun 2019 06:14:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="m+poZlhZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 309BD20652 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=2YgyhL6Iks85aazUrnCPmx/bycRYNADNU0WJii9Hhz0=; b=m+poZlhZWq3nqM 5Yd9c6fo47mD0VGZyp269crh4F4bTNgRKmMwnGUhnGock6pptrdAYEa6Ml//fp1mVBLq8goqCDINQ ostVTYnV/tYsS9M+ffRwMZUb80W/nXSNnmj0r49azC8J2pwzQ6J9xoCAFv/+K7YdqiiyydIttsADQ vM4fWnVcL1ATnswKtSFe+7hy1lA+mXHSw70prIURI9jlVKuzkCtYtIHZ0WSLjNlCxehmLH04Dz2v+ jKB4nWq0rExhKOZgxgXs0nfwyXvWFLpxL7C744gCQ+o62MJQXnjomDb4uXJCqaeHA73VHJlV1Viz4 QmenbDLSJoZl3RlA9GPA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hfeiV-0000hg-Gn; Tue, 25 Jun 2019 06:14:07 +0000 Received: from verein.lst.de ([213.95.11.211] helo=newverein.lst.de) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hfeiS-0000hJ-Ch; Tue, 25 Jun 2019 06:14:05 +0000 Received: by newverein.lst.de (Postfix, from userid 2407) id 4350A68B02; Tue, 25 Jun 2019 08:13:32 +0200 (CEST) Date: Tue, 25 Jun 2019 08:13:32 +0200 From: Christoph Hellwig To: Vladimir Murzin Subject: Re: [PATCH 1/7] arm-nommu: remove the partial DMA_ATTR_NON_CONSISTENT support Message-ID: <20190625061332.GC28986@lst.de> References: <20190614144431.21760-1-hch@lst.de> <20190614144431.21760-2-hch@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190624_231404_577600_F6B8E3A7 X-CRM114-Status: GOOD ( 11.89 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jonas Bonn , linux-xtensa@linux-xtensa.org, linux-parisc@vger.kernel.org, Vineet Gupta , Helge Deller , linux-kernel@vger.kernel.org, Stefan Kristiansson , iommu@lists.linux-foundation.org, openrisc@lists.librecores.org, Stafford Horne , linux-snps-arc@lists.infradead.org, Christoph Hellwig , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jun 24, 2019 at 03:23:08PM +0100, Vladimir Murzin wrote: > On 6/14/19 3:44 PM, Christoph Hellwig wrote: > > The arm-nommu DMA code supports DMA_ATTR_NON_CONSISTENT allocations, but > > does not provide a cache_sync operation. This means any user of it > > will never be able to actually transfer cache ownership and thus cause > > coherency bugs. > > By the way, Documentation/DMA-attributes.txt doesn't specify cache_sync() as > requirement for DMA_ATTR_NON_CONSISTENT it only states that it is responsibility > of the driver to have all the correct and necessary sync points. True. dma_cache_sync has always been a rather odd interface, as it doesn't specify in what direction we need to sync and doesn't participate in our ownership protocol. So my mid-term plan is to kill it off and replace it with the existing dma_sync_* helpers. This series is the first step towards that. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel