[PATCH 2/2] Use bit-wise majority to recover the contents of ONFI parameter

Jane Wan
2018-04-27T00:22:56Z

Signed-off-by: Jane Wan <Jane.Wan@nokia.com>
---
drivers/mtd/nand/nand_base.c | 35 +++++++++++++++++++++++++++++++----
1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index c2e1232..161b523 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3153,8 +3153,10 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
int *busw)
{
struct nand_onfi_params *p = &chip->onfi_params;
- int i, j;
- int val;
+ int i, j, k, len, val;
+ uint8_t copy[3][256], v8;
+
+ len = (sizeof(*p) > 256) ? 256 : sizeof(*p);

/* Try ONFI for unknown chip or LP */
chip->cmdfunc(mtd, NAND_CMD_READID, 0x20, -1);
@@ -3170,11 +3172,36 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
le16_to_cpu(p->crc)) {
break;
}
+ pr_err("CRC of parameter page %d is not valid\n", i);
+ for (j = 0; j < len; j++)
+ copy[i][j] = ((uint8_t *)p)[j];
}

if (i == 3) {
- pr_err("Could not find valid ONFI parameter page; aborting\n");
- return 0;
+ pr_err("Could not find valid ONFI parameter page\n");
+ pr_info("Recover ONFI parameters with bit-wise majority\n");
+ for (j = 0; j < len; j++) {
+ if (copy[0][j] == copy[1][j] ||
+ copy[0][j] == copy[2][j]) {
+ ((uint8_t *)p)[j] = copy[0][j];
+ } else if (copy[1][j] == copy[2][j]) {
+ ((uint8_t *)p)[j] = copy[1][j];
+ } else {
+ ((uint8_t *)p)[j] = 0;
+ for (k = 0; k < 8; k++) {
+ v8 = (copy[0][j] >> k) & 0x1;
+ v8 += (copy[1][j] >> k) & 0x1;
+ v8 += (copy[2][j] >> k) & 0x1;
+ if (v8 > 1)
+ ((uint8_t *)p)[j] |= (1 << k);
+ }
+ }
+ }
+ if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) !=
+ le16_to_cpu(p->crc)) {
+ pr_err("ONFI parameter recovery failed, aborting\n");
+ return 0;
+ }
}

/* Check version */
--
1.7.9.5