[PATCH] ieee1394: speed up of dma_region_sync_for_cpu

[Jim Westfall]

when attempting to find the 'last' part of the dma region continue the 
search from where we left off, instead of starting the search over.

Signed-off-by: Jim Westfall <jwestfall@xxxxxxxxxxxxxxxx>

--- linux-2.6.15.4/drivers/ieee1394/dma.c.orig	2006-03-01 13:37:45.000000000 -0800
+++ linux-2.6.15.4/drivers/ieee1394/dma.c	2006-03-01 14:32:16.000000000 -0800
@@ -137,12 +137,12 @@ void dma_region_free(struct dma_region *
 
 /* find the scatterlist index and remaining offset corresponding to a
    given offset from the beginning of the buffer */
-static inline int dma_region_find(struct dma_region *dma, unsigned long offset, unsigned long *rem)
+static inline int dma_region_find(struct dma_region *dma, unsigned long offset, unsigned int start, unsigned long *rem)
 {
 	int i;
 	unsigned long off = offset;
 
-	for (i = 0; i < dma->n_dma_pages; i++) {
+	for (i = start; i < dma->n_dma_pages; i++) {
 		if (off < sg_dma_len(&dma->sglist[i])) {
 			*rem = off;
 			break;
@@ -160,7 +160,7 @@ dma_addr_t dma_region_offset_to_bus(stru
 {
 	unsigned long rem = 0;
 
-	struct scatterlist *sg = &dma->sglist[dma_region_find(dma, offset, &rem)];
+	struct scatterlist *sg = &dma->sglist[dma_region_find(dma, offset, 0, &rem)];
 	return sg_dma_address(sg) + rem;
 }
 
@@ -172,8 +172,8 @@ void dma_region_sync_for_cpu(struct dma_
 	if (!len)
 		len = 1;
 
-	first = dma_region_find(dma, offset, &rem);
-	last = dma_region_find(dma, offset + len - 1, &rem);
+	first = dma_region_find(dma, offset, 0, &rem);
+	last = dma_region_find(dma, rem + len - 1, first, &rem);
 
 	pci_dma_sync_sg_for_cpu(dma->dev, &dma->sglist[first], last - first + 1, dma->direction);
 }
@@ -186,8 +186,8 @@ void dma_region_sync_for_device(struct d
 	if (!len)
 		len = 1;
 
-	first = dma_region_find(dma, offset, &rem);
-	last = dma_region_find(dma, offset + len - 1, &rem);
+	first = dma_region_find(dma, offset, 0, &rem);
+	last = dma_region_find(dma, rem + len - 1, first, &rem);
 
 	pci_dma_sync_sg_for_device(dma->dev, &dma->sglist[first], last - first + 1, dma->direction);
 }
-
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