Per ONFI specification (Rev. 4.0), if all parameter pages have invalid CRC values, the bit-wise majority may be used to recover the contents of the parameter pages from the parameter page copies present.
Signed-off-by: Jane Wan <jane....@nokia.com> --- v7: change debug print messages v6: support the cases that srcbufs are not contiguous v5: make the bit-wise majority functon generic v4: move the bit-wise majority code in a separate function v3: fix warning message detected by kbuild test robot v2: rebase the changes on top of v4.17-rc1 drivers/mtd/nand/raw/nand_base.c | 50 ++++++++++++++++++++++++++++++++++---- 1 file changed, 45 insertions(+), 5 deletions(-) diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index 72f3a89..b43b784 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -5087,6 +5087,35 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip, } /* + * Recover data with bit-wise majority + */ +static void nand_bit_wise_majority(const void **srcbufs, + unsigned int nsrcbufs, + void *dstbuf, + unsigned int bufsize) +{ + int i, j, k; + + for (i = 0; i < bufsize; i++) { + u8 cnt, val; + + val = 0; + for (j = 0; j < 8; j++) { + cnt = 0; + for (k = 0; k < nsrcbufs; k++) { + const u8 *srcbuf = srcbufs[k]; + + if (srcbuf[i] & BIT(j)) + cnt++; + } + if (cnt > nsrcbufs / 2) + val |= BIT(j); + } + ((u8 *)dstbuf)[i] = val; + } +} + +/* * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise. */ static int nand_flash_detect_onfi(struct nand_chip *chip) @@ -5102,7 +5131,7 @@ static int nand_flash_detect_onfi(struct nand_chip *chip) return 0; /* ONFI chip: allocate a buffer to hold its parameter page */ - p = kzalloc(sizeof(*p), GFP_KERNEL); + p = kzalloc((sizeof(*p) * 3), GFP_KERNEL); if (!p) return -ENOMEM; @@ -5113,21 +5142,32 @@ static int nand_flash_detect_onfi(struct nand_chip *chip) } for (i = 0; i < 3; i++) { - ret = nand_read_data_op(chip, p, sizeof(*p), true); + ret = nand_read_data_op(chip, &p[i], sizeof(*p), true); if (ret) { ret = 0; goto free_onfi_param_page; } - if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) == + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)&p[i], 254) == le16_to_cpu(p->crc)) { + if (i) + memcpy(p, &p[i], sizeof(*p)); break; } } if (i == 3) { - pr_err("Could not find valid ONFI parameter page; aborting\n"); - goto free_onfi_param_page; + const void *srcbufs[3] = {p, p + 1, p + 2}; + + pr_warn("Could not find a valid ONFI parameter page, trying bit-wise majority to recover it\n"); + nand_bit_wise_majority(srcbufs, ARRAY_SIZE(srcbufs), p, + sizeof(*p)); + + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)p, 254) != + le16_to_cpu(p->crc)) { + pr_err("ONFI parameter recovery failed, aborting\n"); + goto free_onfi_param_page; + } } /* Check version */ -- 1.7.9.5