From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751442AbcABKkE (ORCPT <rfc822;w@1wt.eu>);
	Sat, 2 Jan 2016 05:40:04 -0500
Received: from pandora.arm.linux.org.uk ([78.32.30.218]:35553 "EHLO
	pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751039AbcABKkC (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Sat, 2 Jan 2016 05:40:02 -0500
Date: Sat, 2 Jan 2016 10:39:48 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        dmaengine@vger.kernel.org, Lars-Peter Clausen <lars@metafoo.de>,
        Vinod Koul <vinod.koul@intel.com>,
        Nicolas Ferre <nicolas.ferre@atmel.com>,
        Christoph Hellwig <hch@lst.de>,
        "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [Question about DMA] Consistent memory?
Message-ID: <20160102103948.GR8644@n2100.arm.linux.org.uk>
References: <CAK7LNASd1amcHinXzYy=8mtYbnHUY1G_v=fthpachAVSyjqPZA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAK7LNASd1amcHinXzYy=8mtYbnHUY1G_v=fthpachAVSyjqPZA@mail.gmail.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

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 think you have answers to your other points by others in this thread.

Thanks.

-- 
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.