From a7aea373b4ca428f1be2c1fedd2f26c8e3f2864d Mon Sep 17 00:00:00 2001 From: "Ira W. Snyder" Date: Thu, 23 Apr 2009 16:17:54 -0700 Subject: 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 Acked-by: Timur Tabi Acked-by: Kumar Gala Signed-off-by: Dan Williams --- drivers/dma/fsldma.h | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/dma/fsldma.h') diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h index 4f21a512d848..dc7f26865797 100644 --- a/drivers/dma/fsldma.h +++ b/drivers/dma/fsldma.h @@ -38,6 +38,7 @@ /* Special MR definition for MPC8349 */ #define FSL_DMA_MR_EOTIE 0x00000080 +#define FSL_DMA_MR_PRC_RM 0x00000800 #define FSL_DMA_SR_CH 0x00000020 #define FSL_DMA_SR_PE 0x00000010 -- cgit v1.2.3