Re: [PATCH] fsldma: use PCI Read Multiple command

Timur Tabi
2009-04-27T14:39:23Z

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