Messages in this thread | | | Date | Mon, 27 Apr 2009 15:48:21 +0800 | Subject | Re: [PATCH] fsldma: use PCI Read Multiple command | From | Li Yang <> |
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On Sat, Apr 25, 2009 at 2:35 AM, Ira Snyder <iws@ovro.caltech.edu> 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. > > The slowdown due to using PCI Read Line was only observed when a PCI-to-PCI > bridge was between the devices trying to communicate. > > A simple test driver showed an increase from 4MB/sec to 116MB/sec when > performing DMA over the PCI bus. Using DMA to transfer between blocks of > local SDRAM showed no change in performance with this patch. The dmatest > driver was also used to verify the correctness of the transfers, and showed > no errors. > > Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Acked-by: Li Yang <leoli@freescale.com>
Thanks, Leo
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