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authorIra W. Snyder <iws@ovro.caltech.edu>2009-04-23 16:17:54 -0700
committerDan Williams <dan.j.williams@intel.com>2009-06-16 11:29:17 -0700
commita7aea373b4ca428f1be2c1fedd2f26c8e3f2864d (patch)
treeca05d01f882aee0f5fd54fd6f649ca0ab566f938 /kernel
parent07a2039b8eb0af4ff464efd3dfd95de5c02648c6 (diff)
fsldma: use PCI Read Multiple command
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: Timur Tabi <timur@freescale.com> Acked-by: Kumar Gala <galak@kernel.crashing.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'kernel')
0 files changed, 0 insertions, 0 deletions