When using BCH8 decoding, bitflips in an empty page are
not checked. This can cause issues if UBI/UBIFS are used.
Extend the omap_correct_bch() function to check for them.
Code is based on linux mainline mtd/nand/omap2.c driver.
Signed-off-by: Teresa Remmet <t.remmet@xxxxxxxxx>
---
drivers/mtd/nand/nand_omap_gpmc.c | 62 ++++++++++++++++++++++++++-------------
1 file changed, 42 insertions(+), 20 deletions(-)
diff --git a/drivers/mtd/nand/nand_omap_gpmc.c b/drivers/mtd/nand/nand_omap_gpmc.c
index 1d1de5b..a4e6452 100644
--- a/drivers/mtd/nand/nand_omap_gpmc.c
+++ b/drivers/mtd/nand/nand_omap_gpmc.c
@@ -87,6 +87,9 @@
#define BCH8_MAX_ERROR 8 /* upto 8 bit correctable */
+static const uint8_t bch8_vector[] = {0xf3, 0xdb, 0x14, 0x16, 0x8b, 0xd2,
+ 0xbe, 0xcc, 0xac, 0x6b, 0xff, 0x99, 0x7b};
+
int omap_gpmc_decode_bch(int select_4_8, unsigned char *ecc, unsigned int *err_loc);
static const char *ecc_mode_strings[] = {
@@ -294,8 +297,11 @@ static int omap_correct_bch(struct mtd_info *mtd, uint8_t *dat,
{
struct nand_chip *nand = (struct nand_chip *)(mtd->priv);
struct gpmc_nand_info *oinfo = (struct gpmc_nand_info *)(nand->priv);
- int i, j, eccflag, count, totalcount, actual_eccsize;
+ int i, j, eccflag, totalcount, actual_eccsize;
+ const uint8_t *erased_ecc_vec;
unsigned int err_loc[8];
+ int bitflip_count;
+ int bch_max_err;
int eccsteps = oinfo->nand.ecc.steps;
int eccsize = oinfo->nand.ecc.bytes;
@@ -304,9 +310,13 @@ static int omap_correct_bch(struct mtd_info *mtd, uint8_t *dat,
case OMAP_ECC_BCH8_CODE_HW:
eccsize /= eccsteps;
actual_eccsize = eccsize;
+ erased_ecc_vec = bch8_vector;
+ bch_max_err = BCH8_MAX_ERROR;
break;
case OMAP_ECC_BCH8_CODE_HW_ROMCODE:
actual_eccsize = eccsize - 1;
+ erased_ecc_vec = bch8_vector;
+ bch_max_err = BCH8_MAX_ERROR;
break;
default:
dev_err(oinfo->pdev, "invalid driver configuration\n");
@@ -316,37 +326,49 @@ static int omap_correct_bch(struct mtd_info *mtd, uint8_t *dat,
totalcount = 0;
for (i = 0; i < eccsteps; i++) {
- /* check if any ecc error */
+ bool is_error_reported = false;
+ bitflip_count = 0;
eccflag = 0;
+
+ /* check for any ecc error */
for (j = 0; (j < actual_eccsize) && (eccflag == 0); j++) {
- if (calc_ecc[j] != 0)
+ if (calc_ecc[j] != 0) {
eccflag = 1;
+ break;
+ }
}
if (eccflag == 1) {
- eccflag = 0;
- for (j = 0; (j < actual_eccsize) &&
- (eccflag == 0); j++)
- if (read_ecc[j] != 0xFF)
- eccflag = 1;
+ if (memcmp(calc_ecc, erased_ecc_vec, actual_eccsize) == 0) {
+ /*
+ * calc_ecc[] matches pattern for ECC
+ * (all 0xff) so this is definitely
+ * an erased-page
+ */
+ } else {
+ bitflip_count = nand_check_erased_ecc_chunk(
+ dat, oinfo->nand.ecc.size, read_ecc,
+ eccsize, NULL, 0, bch_max_err);
+ if (bitflip_count < 0)
+ is_error_reported = true;
+ }
}
- count = 0;
- if (eccflag == 1) {
- count = omap_gpmc_decode_bch(1, calc_ecc, err_loc);
- if (count < 0)
- return count;
- else
- totalcount += count;
- }
+ if (is_error_reported) {
+ bitflip_count = omap_gpmc_decode_bch(1,
+ calc_ecc, err_loc);
+ if (bitflip_count < 0)
+ return bitflip_count;
- for (j = 0; j < count; j++) {
- if (err_loc[j] < 4096)
- dat[err_loc[j] >> 3] ^=
+ for (j = 0; j < bitflip_count; j++) {
+ if (err_loc[j] < 4096)
+ dat[err_loc[j] >> 3] ^=
1 << (err_loc[j] & 7);
- /* else, not interested to correct ecc */
+ /* else, not interested to correct ecc */
+ }
}
+ totalcount += bitflip_count;
calc_ecc = calc_ecc + actual_eccsize;
read_ecc = read_ecc + eccsize;
dat += 512;
--
1.9.1
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