With the previous code, the remaining prefetched sectors were read again after
each sector. With this patch, each sector is read only once, thus making the
prefetch useful.

Signed-off-by: Benoît Thébaudeau <benoit.thebaud...@advansee.com>
Cc: Wolfgang Denk <w...@denx.de>
---
 .../fs/fat/fat.c                                   |   59 +++++++++++---------
 1 file changed, 33 insertions(+), 26 deletions(-)

diff --git u-boot-66714b1.orig/fs/fat/fat.c u-boot-66714b1/fs/fat/fat.c
index e628cf7..fcce412 100644
--- u-boot-66714b1.orig/fs/fat/fat.c
+++ u-boot-66714b1/fs/fat/fat.c
@@ -777,7 +777,7 @@ do_fat_read (const char *filename, void *buffer, unsigned 
long maxsize,
        volume_info volinfo;
        fsdata datablock;
        fsdata *mydata = &datablock;
-       dir_entry *dentptr;
+       dir_entry *dentptr = NULL;
        __u16 prevcksum = 0xffff;
        char *subname = "";
        __u32 cursect;
@@ -876,19 +876,21 @@ do_fat_read (const char *filename, void *buffer, unsigned 
long maxsize,
        while (1) {
                int i;
 
-               debug("FAT read sect=%d, clust_size=%d, DIRENTSPERBLOCK=%zd\n",
-                       cursect, mydata->clust_size, DIRENTSPERBLOCK);
+               if (j == 0) {
+                       debug("FAT read sect=%d, clust_size=%d, 
DIRENTSPERBLOCK=%zd\n",
+                               cursect, mydata->clust_size, DIRENTSPERBLOCK);
 
-               if (disk_read(cursect,
-                               (mydata->fatsize == 32) ?
-                               (mydata->clust_size) :
-                               PREFETCH_BLOCKS,
-                               do_fat_read_block) < 0) {
-                       debug("Error: reading rootdir block\n");
-                       goto exit;
-               }
+                       if (disk_read(cursect,
+                                       (mydata->fatsize == 32) ?
+                                       (mydata->clust_size) :
+                                       PREFETCH_BLOCKS,
+                                       do_fat_read_block) < 0) {
+                               debug("Error: reading rootdir block\n");
+                               goto exit;
+                       }
 
-               dentptr = (dir_entry *) do_fat_read_block;
+                       dentptr = (dir_entry *) do_fat_read_block;
+               }
 
                for (i = 0; i < DIRENTSPERBLOCK; i++) {
                        char s_name[14], l_name[VFAT_MAXLEN_BYTES];
@@ -1030,28 +1032,33 @@ do_fat_read (const char *filename, void *buffer, 
unsigned long maxsize,
                 * completely processed.
                 */
                ++j;
-               int fat32_end = 0;
-               if ((mydata->fatsize == 32) && (j == mydata->clust_size)) {
-                       int nxtsect = 0;
-                       int nxt_clust = 0;
+               int rootdir_end = 0;
+               if (mydata->fatsize == 32) {
+                       if (j == mydata->clust_size) {
+                               int nxtsect = 0;
+                               int nxt_clust = 0;
 
-                       nxt_clust = get_fatent(mydata, root_cluster);
-                       fat32_end = CHECK_CLUST(nxt_clust, 32);
+                               nxt_clust = get_fatent(mydata, root_cluster);
+                               rootdir_end = CHECK_CLUST(nxt_clust, 32);
 
-                       nxtsect = mydata->data_begin +
-                               (nxt_clust * mydata->clust_size);
+                               nxtsect = mydata->data_begin +
+                                       (nxt_clust * mydata->clust_size);
 
-                       root_cluster = nxt_clust;
+                               root_cluster = nxt_clust;
 
-                       cursect = nxtsect;
-                       j = 0;
+                               cursect = nxtsect;
+                               j = 0;
+                       }
                } else {
-                       cursect++;
+                       if (j == PREFETCH_BLOCKS)
+                               j = 0;
+
+                       rootdir_end = (++cursect - mydata->rootdir_sect >=
+                                      rootdir_size);
                }
 
                /* If end of rootdir reached */
-               if ((mydata->fatsize == 32 && fat32_end) ||
-                   (mydata->fatsize != 32 && j == rootdir_size)) {
+               if (rootdir_end) {
                        if (dols == LS_ROOT) {
                                printf("\n%d file(s), %d dir(s)\n\n",
                                       files, dirs);
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