evie/android_kernel_oneplus_msm8998
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mtd: nand: use ECC, if present, when scanning OOB

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scan_read_raw_oob() is used in only in places where the MTD_OPS_PLACE_OOB mode
is preferable to MTD_OPS_RAW mode, so use MTD_OPS_PLACE_OOB instead.
MTD_OPS_PLACE_OOB provides the same functionality with the potential[1] added
bonus of error correction.

This brings scan_block_full() in line with scan_block_fast() so that they
both read bad block markers with MTD_OPS_PLACE_OOB. This can help in
preventing 0xff markers (in good blocks) from being interpreted as bad
block indicators in the presence of a single bitflip.

Note that ECC error codes (EUCLEAN or EBADMSG) are already silently
ignored in all users of scan_read_raw_oob().

[1] Few  drivers perform proper error correction on OOB data. In those
    cases, the use of MTD_OPS_RAW vs. MTD_OPS_PLACE_OOB is not
    significant.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Brian Norris 2012-06-22 16:35:45 -07:00 • committed by David Woodhouse
parent 491ed06f33
commit a7e68834fc
1 changed files with 20 additions and 7 deletions
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27
drivers/mtd/nand/nand_bbt.c
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@ -289,14 +289,24 @@ static int scan_read_raw_data(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
return mtd_read(mtd, offs, len, &retlen, buf); return mtd_read(mtd, offs, len, &retlen, buf);
} }
/* Scan read raw data from flash */ /**
* scan_read_raw_oob - [GENERIC] Scan data+OOB region to buffer
* @mtd: MTD device structure
* @buf: temporary buffer
* @offs: offset at which to scan
* @len: length of data region to read
*
* Scan read data from data+OOB. May traverse multiple pages, interleaving
* page,OOB,page,OOB,... in buf. Completes transfer and returns the "strongest"
* ECC condition (error or bitflip). May quit on the first (non-ECC) error.
*/
static int scan_read_raw_oob(struct mtd_info *mtd, uint8_t *buf, loff_t offs, static int scan_read_raw_oob(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
size_t len) size_t len)
{ {
struct mtd_oob_ops ops; struct mtd_oob_ops ops;
int res; int res, ret = 0;
ops.mode = MTD_OPS_RAW; ops.mode = MTD_OPS_PLACE_OOB;
ops.ooboffs = 0; ops.ooboffs = 0;
ops.ooblen = mtd->oobsize; ops.ooblen = mtd->oobsize;
@ -306,15 +316,18 @@ static int scan_read_raw_oob(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
ops.oobbuf = buf + ops.len; ops.oobbuf = buf + ops.len;
res = mtd_read_oob(mtd, offs, &ops); res = mtd_read_oob(mtd, offs, &ops);
if (res) {
if (res) if (!mtd_is_bitflip_or_eccerr(res))
return res; return res;
else if (mtd_is_eccerr(res) || !ret)
ret = res;
}
buf += mtd->oobsize + mtd->writesize; buf += mtd->oobsize + mtd->writesize;
len -= mtd->writesize; len -= mtd->writesize;
offs += mtd->writesize; offs += mtd->writesize;
} }
return 0; return ret;
} }
static int scan_read_raw(struct mtd_info *mtd, uint8_t *buf, loff_t offs, static int scan_read_raw(struct mtd_info *mtd, uint8_t *buf, loff_t offs,