[PATCH] fsldma: use PCI Read Multiple command
dwh at ovro.caltech.edu
Tue Apr 28 06:41:35 EST 2009
>> PRC_RM - PCI read multiple
>> The default PCI read command used by the DMA controller is
>> PCI Read (PCI command 6h). When the burst length is 32-bytes
>> or longer, PCI Read Line (PCI command Eh) is used (undocumented
>> feature of the controller). Using PCI read multiple
>> (PCI command Ch) results in high-performance across PCI
>> bridges. DMA transfers to non-prefetchable PCI registers
>> should not result in prefetched reads, even when using
>> the PCI read multiple command.
> I was thinking more along the lines of:
> "This driver tells the DMA controller to use the PCI Read Multiple
> command, instead of the PCI Read Line command, for PCI read operations.
> Please be aware that this setting may result in read pre-fetching on
> some platforms."
Ira will add your comment to the body of the code near
the PRC_RM command and submit a new patch.
More information about the Linuxppc-dev