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>

diff --git a/drivers/ieee1394/dma.c b/drivers/ieee1394/dma.c
index 9fb2769d9abca9b25f3e136a79a48609ff5ee0dc..ca5167de707d645de7f3305bdfc61ef2434c678b 100644 (file)
--- 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);