ieee1394: speed up of dma_region_sync_for_cpu

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@surrealistic.net>
Signed-off-by: Ben Collins <bcollins@ubuntu.com>

1 files changed, 9 insertions, 9 deletions

diff --git a/drivers/ieee1394/dma.c b/drivers/ieee1394/dma.c
index 9fb2769d9abc..ca5167de707d 100644
--- a/drivers/ieee1394/dma.c
+++ b/drivers/ieee1394/dma.c
@@ -145,12 +145,12 @@ void dma_region_free(struct dma_region *dma)
 /* 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)
+                                  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;
@@ -170,7 +170,7 @@ dma_addr_t dma_region_offset_to_bus(struct dma_region * dma,
         unsigned long rem = 0;
 
         struct scatterlist *sg =
-            &dma->sglist[dma_region_find(dma, offset, &rem)];
+            &dma->sglist[dma_region_find(dma, offset, 0, &rem)];
         return sg_dma_address(sg) + rem;
 }
 
@@ -178,13 +178,13 @@ void dma_region_sync_for_cpu(struct dma_region *dma, unsigned long offset,
                              unsigned long len)
 {
         int first, last;
-        unsigned long rem;
+        unsigned long rem = 0;
 
         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);
@@ -194,13 +194,13 @@ void dma_region_sync_for_device(struct dma_region *dma, unsigned long offset,
                                 unsigned long len)
 {
         int first, last;
-        unsigned long rem;
+        unsigned long rem = 0;
 
         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);