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Message-ID: <49F614FC.70000@freescale.com> Date: Mon, 27 Apr 2009 15:26:36 -0500 From: Timur Tabi <timur@...escale.com> To: David Hawkins <dwh@...o.caltech.edu> CC: Liu Dave-R63238 <DaveLiu@...escale.com>, Ira Snyder <iws@...o.caltech.edu>, linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org, Dan Williams <dan.j.williams@...el.com> Subject: Re: [PATCH] fsldma: use PCI Read Multiple command David Hawkins wrote: > 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." -- Timur Tabi Linux kernel developer at Freescale -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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