From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Subject: Re: [PATCHv3 net-next 21/22] net: mvpp2: set dma mask and coherent
 dma mask on PPv2.2
Date: Tue, 7 Mar 2017 19:12:01 +0100
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To: David Laight <David.Laight@ACULAB.COM>
Cc: Mark Rutland <mark.rutland@arm.com>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, Yehuda Yitschak <yehuday@marvell.com>, Russell King <linux@arm.linux.org.uk>, Jason Cooper <jason@lakedaemon.net>, Pawel Moll <pawel.moll@arm.com>, Ian Campbell <ijc+devicetree@hellion.org.uk>, "netdev@vger.kernel.org" <netdev@vger.kernel.org>, Hanna Hawa <hannah@marvell.com>, Nadav Haklai <nadavh@marvell.com>, Rob Herring <robh+dt@kernel.org>, Andrew Lunn <andrew@lunn.ch>, Kumar Gala <galak@codeaurora.org>, Gregory Clement <gregory.clement@free-electrons.com>, Stefan Chulski <stefanc@marvell.com>, Marcin Wojtas <mw@semihalf.com>, "David S. Miller" <davem@davemloft.net>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
List-Id: devicetree@vger.kernel.org

Hello,

On Tue, 7 Mar 2017 17:24:21 +0000, David Laight wrote:

> Are the coherent mappings just used for ring structures?
> If it might be reasonable to allocate them as a single entity,
> thus guaranteeing they all reside in a single 4G region.

Do we have the guarantee that a DMA coherent allocation will not span a
4G boundary?

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com