Hi Boris, I've sent v5 of the patch based on your comment.
Thanks. Jane > -----Original Message----- > From: Boris Brezillon [mailto:[email protected]] > Sent: Wednesday, May 09, 2018 7:19 AM > To: Wan, Jane (Nokia - US/Sunnyvale) <[email protected]> > Cc: [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected]; [email protected]; linux- > [email protected]; Bos, Ties (Nokia - US/Sunnyvale) <[email protected]> > Subject: Re: [PATCH v4 2/2] mtd: rawnand: use bit-wise majority to recover the > contents of ONFI parameter > > On Tue, 8 May 2018 14:19:54 -0700 > Jane Wan <[email protected]> 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 <[email protected]> > > --- > > drivers/mtd/nand/raw/nand_base.c | 49 > ++++++++++++++++++++++++++++++++++---- > > 1 file changed, 44 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/mtd/nand/raw/nand_base.c > > b/drivers/mtd/nand/raw/nand_base.c > > index 72f3a89..dfc341c 100644 > > --- a/drivers/mtd/nand/raw/nand_base.c > > +++ b/drivers/mtd/nand/raw/nand_base.c > > @@ -5086,6 +5086,38 @@ static int > nand_flash_detect_ext_param_page(struct nand_chip *chip, > > return ret; > > } > > > > +#define GET_BIT(bit, val) (((val) >> (bit)) & 0x01) > > + > > +/* > > + * Recover NAND parameter page with bit-wise majority */ static int > > +onfi_recover_param(struct nand_onfi_params *p, int pages) > > I had something more generic in mind: > > static void nand_bit_wise_majority(const void **srcbufs, > void *dstbuf, > unsigned int nbufs, > unsigned int bufsize) > { > ... > } > > And then you do the crc check in nand_flash_detect_onfi(). > > The reason I'm asking that is because I'm almost sure we'll re-use this > functions > for extended param pages, and also for vendor specific data (we already have a > byte-wise majority check in the hynix driver, so I wouldn't be surprised if > other > vendors decided to use a bit-wise approach for some of their OTP area). [Jane] Modified the function as suggested in v5. > > > +{ > > + int i, j, k; > > + u8 v, m; > > + u8 *buf; > > + > > + buf = (u8 *)p; > > + for (i = 0; i < sizeof(*p); i++) { > > + v = 0; > > + for (j = 0; j < 8; j++) { > > + m = 0; > > + for (k = 0; k < pages; k++) > > + m += GET_BIT(j, buf[k*sizeof(*p) + i]); > > + if (m > pages/2) > > + v |= BIT(j); > > + } > > + ((u8 *)p)[i] = v; > > + } > > + > > + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)p, 254) == > > + le16_to_cpu(p->crc)) { > > + return 1; > > + } > > + > > + return 0; > > +} > > + > > /* > > * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 > > otherwise. > > */ > > @@ -5102,7 +5134,7 @@ 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 +5145,28 @@ 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; > > + pr_err("Could not find valid ONFI parameter page\n"); > > + pr_info("Recover ONFI params with bit-wise majority\n"); > > + ret = onfi_recover_param(p, 3); > > + if (ret == 0) { > > + pr_err("ONFI parameter recovery failed, aborting\n"); > > + goto free_onfi_param_page; > > + } > > } > > > > /* Check version */
