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From: Timur Tabi <timur-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
To: Mitch Bradley <wmb-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org>
Cc: Yoder Stuart-B08248
	<B08248-KZfg59tc24xl57MIdRCFDg@public.gmane.org>,
	devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Subject: Re: question about dma-ranges
Date: Tue, 26 Oct 2010 20:37:55 -0500	[thread overview]
Message-ID: <AANLkTikTu_p0-Uk7=FuUay4mvCEEU0e9V5eY6bjuK5RQ@mail.gmail.com> (raw)
In-Reply-To: <4CC77784.2070701-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org>

On Tue, Oct 26, 2010 at 7:51 PM, Mitch Bradley <wmb-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org> wrote:
>  It's probably unnecessary on modern machines, but old PCs were fairly
> restrictive about DMA addresses due to short counters.  The buses on which
> 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

  parent reply	other threads:[~2010-10-27  1:37 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-27  0:48 question about dma-ranges Yoder Stuart-B08248
     [not found] ` <9696D7A991D0824DBA8DFAC74A9C5FA306911C5F-ofAVchDyotYzzZk0BCvKg5jmvxFtTJ+o0e7PPNI6Mm0@public.gmane.org>
2010-10-27  0:51   ` Mitch Bradley
     [not found]     ` <4CC77784.2070701-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org>
2010-10-27  1:37       ` Timur Tabi [this message]
     [not found]         ` <AANLkTikTu_p0-Uk7=FuUay4mvCEEU0e9V5eY6bjuK5RQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-10-27  2:42           ` David Gibson
2010-10-27 19:46             ` Scott Wood
     [not found]               ` <20101027144602.2c5ef098-N/eSCTBpGwP7j4BuCOFQISmX4OfbXNuMKnGXBo5VDl8@public.gmane.org>
2010-10-27 19:47                 ` Timur Tabi

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