From mboxrd@z Thu Jan 1 00:00:00 1970 From: Timur Tabi Subject: Re: question about dma-ranges Date: Tue, 26 Oct 2010 20:37:55 -0500 Message-ID: References: <9696D7A991D0824DBA8DFAC74A9C5FA306911C5F@az33exm25.fsl.freescale.net> <4CC77784.2070701@firmworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <4CC77784.2070701-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Mitch Bradley Cc: Yoder Stuart-B08248 , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org List-Id: devicetree@vger.kernel.org On Tue, Oct 26, 2010 at 7:51 PM, Mitch Bradley wrote: > =A0It's probably unnecessary on modern machines, but old PCs were fairly > restrictive about DMA addresses due to short counters. =A0The buses on wh= ich > such restrictions applied are no longer at the root level, but they were > once there... It's still necessary. The QE, which we ship on several of our current parts, can only DMA to/from 32-bit addresses, even on SOCs that support 36-bit addressing for everything else. -- = Timur Tabi Linux kernel developer at Freescale