[PATCH] fsldma: use PCI Read Multiple command

Liu Dave-R63238 DaveLiu at freescale.com
Tue Apr 28 11:31:08 EST 2009


> > 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.

How about FIFO RAM case?



More information about the Linuxppc-dev mailing list