mtd: nand: remove NAND_BBT_SCANBYTE1AND6 option

This patch reverts most of:
    commit 58373ff0afff4cc8ac40608872995f4d87eb72ec
    mtd: nand: more BB Detection refactoring and dynamic scan options

According to the discussion at:
    http://lists.infradead.org/pipermail/linux-mtd/2011-May/035696.html
the NAND_BBT_SCANBYTE1AND6 flag, although technically valid, can break
some existing ECC layouts that use the 6th byte in the OOB for ECC data.
Furthermore, we apparently do not need to scan both bytes 1 and 6 in
the OOB region of the devices under consideration; instead, we only need
to scan one or the other.

Thus, the NAND_BBT_SCANBYTE1AND6 flag is at best unnecessary and at
worst a regression.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 1 insertions, 31 deletions

diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index ccbeaa1e4a8e..5ffb9a4632ca 100644
--- a/drivers/mtd/nand/nand_bbt.c
+++ b/drivers/mtd/nand/nand_bbt.c
@@ -114,28 +114,6 @@ static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_desc
                         return -1;
         }
 
-        /* Check both positions 1 and 6 for pattern? */
-        if (td->options & NAND_BBT_SCANBYTE1AND6) {
-                if (td->options & NAND_BBT_SCANEMPTY) {
-                        p += td->len;
-                        end += NAND_SMALL_BADBLOCK_POS - td->offs;
-                        /* Check region between positions 1 and 6 */
-                        for (i = 0; i < NAND_SMALL_BADBLOCK_POS - td->offs - td->len;
-                                        i++) {
-                                if (*p++ != 0xff)
-                                        return -1;
-                        }
-                }
-                else {
-                        p += NAND_SMALL_BADBLOCK_POS - td->offs;
-                }
-                /* Compare the pattern */
-                for (i = 0; i < td->len; i++) {
-                        if (p[i] != td->pattern[i])
-                                return -1;
-                }
-        }
-
         if (td->options & NAND_BBT_SCANEMPTY) {
                 p += td->len;
                 end += td->len;
@@ -167,13 +145,6 @@ static int check_short_pattern(uint8_t *buf, struct nand_bbt_descr *td)
                 if (p[td->offs + i] != td->pattern[i])
                         return -1;
         }
-        /* Need to check location 1 AND 6? */
-        if (td->options & NAND_BBT_SCANBYTE1AND6) {
-                for (i = 0; i < td->len; i++) {
-                        if (p[NAND_SMALL_BADBLOCK_POS + i] != td->pattern[i])
-                                return -1;
-                }
-        }
         return 0;
 }
 
@@ -1330,8 +1301,7 @@ static struct nand_bbt_descr bbt_mirror_no_bbt_descr = {
         .pattern = mirror_pattern
 };
 
-#define BBT_SCAN_OPTIONS (NAND_BBT_SCANLASTPAGE | NAND_BBT_SCAN2NDPAGE | \
-                NAND_BBT_SCANBYTE1AND6)
+#define BBT_SCAN_OPTIONS (NAND_BBT_SCANLASTPAGE | NAND_BBT_SCAN2NDPAGE)
 /**
  * nand_create_default_bbt_descr - [Internal] Creates a BBT descriptor structure
  * @this:       NAND chip to create descriptor for