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mtd: nand: omap: ecc.correct: omap_elm_correct_data: fix programmed-page bit-flip correction logic

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This patch updates following checks when bit-flips are detected by ELM:

 - Do not evaluate bit-flips when un-correctable bit-flips is reported by ELM,
   because as per [1] when ELM reports an un-correctable bit-flips,
   'number of error' field in its ELM_LOCATION_STATUS register is also invalid.

 - Return with error-code '-EBADMSG' on detection of un-correctable bit-flip.

 - Return with error-code '-EBADMSG' when bit-flips position is outside current
   Sector and OOB area.

[1] ELM IP spec Table-25 ELM_LOCATION_STATUS Register.
    ELM_LOCATION_STATUS[8] = ECC_CORRECTABLE: Error location process exit status
        0x0: ECC error location process failed.
             Number of errors and error locations are invalid.
        0x1: all errors were successfully located.
             Number of errors and error locations are valid.

Tested-by: Stefan Roese <sr@denx.de>
Signed-off-by: Pekon Gupta <pekon@ti.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
This commit is contained in:
Pekon Gupta
2014-03-18 18:56:46 +05:30
committed by Brian Norris
parent b08e1f632c
commit 13fbe0641e
1 changed files with 19 additions and 10 deletions
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29
drivers/mtd/nand/omap2.c
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@@ -1353,6 +1353,7 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data,
int bitflip_count;
bool is_error_reported = false;
u32 bit_pos, byte_pos, error_max, pos;
int err;
switch (info->ecc_opt) {
case OMAP_ECC_BCH4_CODE_HW:
@@ -1434,8 +1435,12 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data,
/* Decode BCH error using ELM module */
elm_decode_bch_error_page(info->elm_dev, ecc_vec, err_vec);
err = 0;
for (i = 0; i < eccsteps; i++) {
if (err_vec[i].error_reported) {
if (err_vec[i].error_uncorrectable) {
pr_err("nand: uncorrectable bit-flips found\n");
err = -EBADMSG;
} else if (err_vec[i].error_reported) {
for (j = 0; j < err_vec[i].error_count; j++) {
switch (info->ecc_opt) {
case OMAP_ECC_BCH4_CODE_HW:
@@ -1457,13 +1462,22 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data,
byte_pos = (error_max - pos - 1) / 8;
if (pos < error_max) {
if (byte_pos < 512)
if (byte_pos < 512) {
pr_debug("bitflip@dat[%d]=%x\n",
byte_pos, data[byte_pos]);
data[byte_pos] ^= 1 << bit_pos;
else
} else {
pr_debug("bitflip@oob[%d]=%x\n",
(byte_pos - 512),
spare_ecc[byte_pos - 512]);
spare_ecc[byte_pos - 512] ^=
1 << bit_pos;
}
} else {
pr_err("invalid bit-flip @ %d:%d\n",
byte_pos, bit_pos);
err = -EBADMSG;
}
/* else, not interested to correct ecc */
}
}
@@ -1475,12 +1489,7 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data,
spare_ecc += ecc->bytes;
}
for (i = 0; i < eccsteps; i++)
/* Return error if uncorrectable error present */
if (err_vec[i].error_uncorrectable)
return -EINVAL;
return stat;
return (err) ? err : stat;
}
/**