On Mon, Apr 27, 2009 at 5:09 PM, Liu Dave-R63238 <dave...@freescale.com> wrote: >> By default, the Freescale 83xx DMA controller uses the PCI Read Line >> command when reading data over the PCI bus. Setting the >> controller to use the PCI Read Multiple command instead allows the >> controller to read much larger bursts of data, which provides a > drastic >> speed increase. > > IIRC, the default for 83xx DMA controller uses the PCI mem read > command, not mem read line. > > 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?
I guess it's not reasonable to use DMA from non-prefetchable memory. So it's up to the driver which uses the DMA engine to prevent from using DMA API on non-prefetchable memory. - Leo _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
