Messages in this thread Patch in this message | | | Date | Thu, 10 May 2018 14:03:11 +0200 | From | Boris Brezillon <> | Subject | Re: [PATCH v5 2/2] mtd: rawnand: use bit-wise majority to recover the contents of ONFI parameter |
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Hi Jane,
Subject prefix should be "[PATCH v5] ...", the 2/2 is no longer valid since you only have one patch here.
On Wed, 9 May 2018 19:46:40 -0700 Jane Wan <Jane.Wan@nokia.com> wrote:
> 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.Wan@nokia.com> > ---
There should be a changelog here describing what has changed in each version of the patch.
> drivers/mtd/nand/raw/nand_base.c | 46 +++++++++++++++++++++++++++++++++----- > 1 file changed, 41 insertions(+), 5 deletions(-) > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c > index 72f3a89..a7c2507 100644 > --- a/drivers/mtd/nand/raw/nand_base.c > +++ b/drivers/mtd/nand/raw/nand_base.c > @@ -5086,6 +5086,34 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip, > return ret; > } > > +#define GET_BIT(bit, val) (((val) >> (bit)) & 0x01)
Not sure we need that macro, see below.
> + > +/* > + * Recover data with bit-wise majority > + */ > +static void nand_bit_wise_majority(const void **srcbufs, > + void *dstbuf, > + unsigned int nbufs, > + unsigned int bufsize)
I'd prefer to have nbufs just after srcbufs and named nsrcbufs:
static void nand_bit_wise_majority(const void **srcbufs, unsigned int nsrcbufs, void *dstbuf, unsigned int bufsize)
> +{ > + int i, j, k; > + u8 v, m; > + u8 *p; > + > + p = *(u8 **)srcbufs;
Nope, I'd like to support the cases where srcbufs are not contiguous, so that does not work.
> + for (i = 0; i < bufsize; i++) { > + v = 0;
You can declare the v variable here, since its scope is limited to the for loop. BTW, v, m, can't we pick better names? I guess v is for val, but I'm not even sure what m stands for.
> + for (j = 0; j < 8; j++) { > + m = 0; > + for (k = 0; k < nbufs; k++) > + m += GET_BIT(j, p[k*bufsize + i]);
for (k = 0; k < nbufs; k++) { const u8 *srcbuf = srcbufs[j];
if (srcbuf[i] & BIT(k)) m++; }
> + if (m > nbufs/2)
Space between operands and operators please
if (m > nbufs / 2)
> + v |= BIT(j); > + } > + ((u8 *)dstbuf)[i] = v; > + } > +} > + > /* > * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise. > */ > @@ -5102,7 +5130,7 @@ 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 +5141,29 @@ 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) {
const void *srcbufs[3] = {p, p + 1, p + 2};
> - pr_err("Could not find valid ONFI parameter page; aborting\n"); > - goto free_onfi_param_page; > + pr_err("Could not find valid ONFI parameter page\n"); > + pr_info("Recover ONFI params with bit-wise majority\n"); > + nand_bit_wise_majority((const void **)&p, p, 3, sizeof(*p));
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 */
Thanks,
Boris
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