From mboxrd@z Thu Jan 1 00:00:00 1970 From: mike.looijmans@topic.nl (Mike Looijmans) Date: Sat, 02 Jan 2016 19:35:32 +0100 Subject: [Question about DMA] Consistent memory? In-Reply-To: <20160102103948.GR8644@n2100.arm.linux.org.uk> References: <20160102103948.GR8644@n2100.arm.linux.org.uk> Message-ID: <56881874.4050907@topic.nl> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 2-1-2016 11:39, Russell King - ARM Linux wrote: > On Thu, Dec 31, 2015 at 04:50:54PM +0900, Masahiro Yamada wrote: >> Hi. >> >> I am new to the Linux DMA APIs. >> >> First, I started by reading Documentation/DMA-API.txt, >> but I am confused with the term "consistent memory". > > Just read "coherent memory" instead - the documentation confusingly uses > the two terms to refer to the same thing. I think there was a patch a > while back to replace "consistent" with "coherent" in this document, > though I'm not sure what happened to it. I wrote that patch. I never got any comments on it, so either I didn't post it to the right people, or no one really cares: http://www.kernelhub.org/?msg=747166&p=2 I still think that if the kernel methods all have "coherent" in their name, we should use the word "coherent" in the documentation as well, and not confuse people even further. So I'd happily repost that patch. -- Mike Looijmans From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751468AbcABSf6 (ORCPT ); Sat, 2 Jan 2016 13:35:58 -0500 Received: from smtp01.mail.online.nl ([194.134.25.71]:43995 "EHLO smtp01.mail.online.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751039AbcABSf4 (ORCPT ); Sat, 2 Jan 2016 13:35:56 -0500 Message-ID: <56881874.4050907@topic.nl> Date: Sat, 02 Jan 2016 19:35:32 +0100 From: Mike Looijmans Organization: Topic User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Russell King - ARM Linux , Masahiro Yamada CC: Lars-Peter Clausen , Vinod Koul , Nicolas Ferre , Linux Kernel Mailing List , Sumit Semwal , "James E.J. Bottomley" , dmaengine@vger.kernel.org, Dan Williams , Christoph Hellwig , linux-arm-kernel Subject: Re: [Question about DMA] Consistent memory? References: <20160102103948.GR8644@n2100.arm.linux.org.uk> In-Reply-To: <20160102103948.GR8644@n2100.arm.linux.org.uk> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2-1-2016 11:39, Russell King - ARM Linux wrote: > On Thu, Dec 31, 2015 at 04:50:54PM +0900, Masahiro Yamada wrote: >> Hi. >> >> I am new to the Linux DMA APIs. >> >> First, I started by reading Documentation/DMA-API.txt, >> but I am confused with the term "consistent memory". > > Just read "coherent memory" instead - the documentation confusingly uses > the two terms to refer to the same thing. I think there was a patch a > while back to replace "consistent" with "coherent" in this document, > though I'm not sure what happened to it. I wrote that patch. I never got any comments on it, so either I didn't post it to the right people, or no one really cares: http://www.kernelhub.org/?msg=747166&p=2 I still think that if the kernel methods all have "coherent" in their name, we should use the word "coherent" in the documentation as well, and not confuse people even further. So I'd happily repost that patch. -- Mike Looijmans