From: Timur Tabi <timur@freescale.com>
To: Liu Dave-R63238 <DaveLiu@freescale.com>
Cc: Ira Snyder <iws@ovro.caltech.edu>,
linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
Dan Williams <dan.j.williams@intel.com>,
Zhang Wei <wei.zhang@freescale.com>
Subject: Re: [PATCH] fsldma: use PCI Read Multiple command
Date: Mon, 27 Apr 2009 09:31:12 -0500 [thread overview]
Message-ID: <ed82fe3e0904270731g2d2519a7mc12e4152c716c0a9@mail.gmail.com> (raw)
In-Reply-To: <D7CCA83BB0796C49BC0BB53B6AB1208928CA1D@zch01exm21.fsl.freescale.net>
On Mon, Apr 27, 2009 at 4:09 AM, Liu Dave-R63238 <DaveLiu@freescale.com> wrote:
> You are assuming the PCI memory space is prefetchable( no side effect)
> for DMA.
> Is it possible that DMA is from non-prefetchable memory space?
This should be a safe assumption for this driver. Remember, this
driver just does offload memcpy, from one region to another. So the
PCI memory that you are reading from should be just a buffer of data,
and there should be side-effect of reading it.
However, I would like to see a comment at the top of the file warning
people that copying from PCI memory will result in prefetched reads.
--
Timur Tabi
Linux kernel developer at Freescale
next prev parent reply other threads:[~2009-04-27 14:31 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-24 18:35 [PATCH] fsldma: use PCI Read Multiple command Ira Snyder
2009-04-27 7:48 ` Li Yang
2009-04-27 9:09 ` Liu Dave-R63238
2009-04-27 10:16 ` Li Yang
2009-04-27 14:31 ` Timur Tabi [this message]
2009-04-27 19:34 ` David Hawkins
2009-04-27 19:40 ` Timur Tabi
2009-04-27 19:48 ` David Hawkins
2009-04-27 19:54 ` Kumar Gala
2009-04-27 20:00 ` David Hawkins
2009-04-27 20:01 ` David Hawkins
2009-04-28 2:06 ` Liu Dave-R63238
2009-04-27 20:02 ` Kumar Gala
2009-04-27 20:12 ` David Hawkins
2009-04-27 20:04 ` Timur Tabi
2009-04-27 20:47 ` Scott Wood
2009-04-27 20:49 ` Timur Tabi
2009-04-27 20:22 ` David Hawkins
2009-04-27 20:26 ` Timur Tabi
2009-04-27 20:41 ` David Hawkins
2009-04-27 20:42 ` Timur Tabi
2009-04-27 20:44 ` David Hawkins
2009-04-27 20:42 ` Ira Snyder
2009-04-27 20:47 ` Timur Tabi
2009-04-27 20:49 ` Dan Williams
2009-06-11 2:45 ` Kumar Gala
2009-06-11 15:17 ` Ira Snyder
2009-06-12 9:23 ` Li Yang
2009-06-12 15:03 ` Kumar Gala
2009-06-12 17:38 ` Dan Williams
2009-06-12 18:01 ` Kumar Gala
2009-04-28 1:48 ` Liu Dave-R63238
2009-04-28 2:08 ` David Hawkins
2009-04-27 21:59 ` Liu Dave-R63238
2009-04-28 1:31 ` Liu Dave-R63238
2009-04-28 1:36 ` David Hawkins
2009-04-28 13:43 ` Timur Tabi
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