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

Boris Brezillon
2018-05-02T10:32:06Z

On Wed, 2 May 2018 12:25:45 +0200
Boris Brezillon <boris.brezillon@bootlin.com> wrote:

> Hi Jane,
>
> On Thu, 26 Apr 2018 17:19:56 -0700
> Jane Wan <Jane.Wan@nokia.com> wrote:
>
> > 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);
> > + }
> > + }
> > + }
>
> I'd like this bit-wise majority algorithm to be generic and moved to
> nand_base.c, because we might want to do the same in the core and make
> it work for any number of repetitions of the PARAM page.

Never mind, I thought you were implementing that in the FSL IFC driver,
but you're actually modifying the core.