From: Dan Malek <ppc6dev@digitaldans.com>
To: Scott Wood <scottwood@freescale.com>
Cc: Timur Tabi <timur.tabi@gmail.com>,
dan.j.williams@intel.com, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fsldma: add support to 36-bit physical address
Date: Tue, 21 Sep 2010 15:05:05 -0700 [thread overview]
Message-ID: <2C3F2C02-35B6-46AF-82DA-44ACCBFB8362@digitaldans.com> (raw)
In-Reply-To: <20100921164944.164ed0af@udp111988uds.am.freescale.net>
On Sep 21, 2010, at 2:49 PM, Scott Wood wrote:
>
> On Tue, 21 Sep 2010 16:43:12 -0500
> Timur Tabi <timur.tabi@gmail.com> wrote:
>
>> Since we don't DMA the descriptors themselves, I just don't see how
>> this patch does anything.
>
> Look in dmaengine.c, there are calls to dma_map_single() and
> dma_map_page(), using what I assume is that same device pointer --
> unless there's confusion between the channel and the controller.
The DMA descriptors are accessed using DMA by the
controller itself. The APIs need to ensure proper coherency
between the CPU and the DMA controller for the
descriptor access. The underlying implementation of the
API will depend upon the hardware capabilities that
ensure this coherency.
-- Dan
next prev parent reply other threads:[~2010-09-21 22:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-21 10:57 Li Yang
2010-09-21 12:55 ` Kumar Gala
2010-09-21 21:24 ` Timur Tabi
2010-09-21 21:34 ` Scott Wood
2010-09-21 21:43 ` Timur Tabi
2010-09-21 21:49 ` Scott Wood
2010-09-21 22:04 ` Timur Tabi
2010-09-21 22:05 ` Dan Malek [this message]
2010-09-21 22:08 ` Timur Tabi
2010-09-21 22:17 ` Scott Wood
2010-09-21 22:34 ` Timur Tabi
2010-09-22 5:41 ` Kumar Gala
2010-09-23 22:11 ` Dan Williams
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