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>

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index a46e9bb847bd0ac52743f14ab07133cc9a98b231..bb2e24b2d6c4b82aa3a7bed13105ea9742780ca2 100644 (file)
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -410,10 +410,11 @@ static int nand_default_block_markbad(struct mtd_info *mtd, loff_t ofs)
        else {
                nand_get_device(chip, mtd, FL_WRITING);
 
-               /* Write to first two pages and to byte 1 and 6 if necessary.
-                * If we write to more than one location, the first error
-                * encountered quits the procedure. We write two bytes per
-                * location, so we dont have to mess with 16 bit access.
+               /*
+                * Write to first two pages if necessary. If we write to more
+                * than one location, the first error encountered quits the
+                * procedure. We write two bytes per location, so we dont have
+                * to mess with 16 bit access.
                 */
                do {
                        chip->ops.len = chip->ops.ooblen = 2;
@@ -423,11 +424,6 @@ static int nand_default_block_markbad(struct mtd_info *mtd, loff_t ofs)
 
                        ret = nand_do_write_oob(mtd, ofs, &chip->ops);
 
-                       if (!ret && (chip->options & NAND_BBT_SCANBYTE1AND6)) {
-                               chip->ops.ooboffs = NAND_SMALL_BADBLOCK_POS
-                                       & ~0x01;
-                               ret = nand_do_write_oob(mtd, ofs, &chip->ops);
-                       }
                        i++;
                        ofs += mtd->writesize;
                } while (!ret && (chip->options & NAND_BBT_SCAN2NDPAGE) &&
@@ -3131,16 +3127,6 @@ ident_done:
                         *maf_id == NAND_MFR_MICRON))
                chip->options |= NAND_BBT_SCAN2NDPAGE;
 
-       /*
-        * Numonyx/ST 2K pages, x8 bus use BOTH byte 1 and 6
-        */
-       if (!(busw & NAND_BUSWIDTH_16) &&
-                       *maf_id == NAND_MFR_STMICRO &&
-                       mtd->writesize == 2048) {
-               chip->options |= NAND_BBT_SCANBYTE1AND6;
-               chip->badblockpos = 0;
-       }
-
        /* Check for AND chips with 4 page planes */
        if (chip->options & NAND_4PAGE_ARRAY)
                chip->erase_cmd = multi_erase_cmd;

diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index ccbeaa1e4a8ed42ccddac88f2780915dc3407736..5ffb9a4632cae9eee625f822e7e0fc16b268276a 100644 (file)
--- 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

diff --git a/include/linux/mtd/bbm.h b/include/linux/mtd/bbm.h
index 57cc0e63714f9651462450db8fbbc78df79b82f1..08ffa2193c0728ffa054d90e24d4f17d38b9904f 100644 (file)
--- a/include/linux/mtd/bbm.h
+++ b/include/linux/mtd/bbm.h
@@ -98,8 +98,6 @@ struct nand_bbt_descr {
 #define NAND_BBT_SCAN2NDPAGE   0x00004000
 /* Search good / bad pattern on the last page of the eraseblock */
 #define NAND_BBT_SCANLASTPAGE  0x00008000
-/* Chip stores bad block marker on BOTH 1st and 6th bytes of OOB */
-#define NAND_BBT_SCANBYTE1AND6 0x00100000
 /* The nand_bbt_descr was created dynamicaly and must be freed */
 #define NAND_BBT_DYNAMICSTRUCT 0x00200000
 /* The bad block table does not OOB for marker */