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Subject[PATCH 10/14] MTD: nand: add ->badblockbits to specify the minimum number of bits in bad block byte to consider the block good
Date
This can be used to protect against bitflips in that field, but now mostly
for smartmedia.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
---
drivers/mtd/nand/nand_base.c | 13 +++++++++----
include/linux/mtd/nand.h | 1 +
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index c393df3..88750a6 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -335,14 +335,18 @@ static int nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip)
bad = cpu_to_le16(chip->read_word(mtd));
if (chip->badblockpos & 0x1)
bad >>= 8;
- if ((bad & 0xFF) != 0xff)
- res = 1;
+ else
+ bad &= 0xFF;
} else {
chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos, page);
- if (chip->read_byte(mtd) != 0xff)
- res = 1;
+ bad = chip->read_byte(mtd);
}

+ if (likely(chip->badblockbits == 8))
+ res = bad != 0xFF;
+ else
+ res = hweight8(bad) < chip->badblockbits;
+
if (getchip)
nand_release_device(mtd);

@@ -2710,6 +2714,7 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
/* Set the bad block position */
chip->badblockpos = mtd->writesize > 512 ?
NAND_LARGE_BADBLOCK_POS : NAND_SMALL_BADBLOCK_POS;
+ chip->badblockbits = 8;

/* Get chip options, preserve non chip based options */
chip->options &= ~NAND_CHIPOPTIONS_MSK;
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index ccab9df..27d998e 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -391,6 +391,7 @@ struct nand_chip {
int subpagesize;
uint8_t cellinfo;
int badblockpos;
+ int badblockbits;

flstate_t state;

--
1.6.3.3


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