[PATCH v2 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to

From: Wan, Jane (Nokia - US/Sunnyvale)
Date: Thu May 03 2018 - 22:09:37 EST

Hi,

The following is the reposting of patch with v2 version indication based on comment on "[PATCH 1/2]" (also in the attachment).

Subject: [PATCH v2 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to
recover the contents of ONFI parameter

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@xxxxxxxxx>
---
drivers/mtd/nand/raw/nand_base.c | 36 ++++++++++++++++++++++++++++++------
1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 72f3a89..464c4fb 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -5086,6 +5086,8 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip,
return ret;
}

+#define GET_BIT(bit, val) (((val) >> (bit)) & 0x01)
+
/*
* Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise.
*/
@@ -5094,7 +5096,8 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
struct mtd_info *mtd = nand_to_mtd(chip);
struct nand_onfi_params *p;
char id[4];
- int i, ret, val;
+ int i, ret, val, pagesize;
+ u8 *buf;

/* Try ONFI for unknown chip or LP */
ret = nand_readid_op(chip, 0x20, id, sizeof(id));
@@ -5102,8 +5105,9 @@ 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);
- if (!p)
+ pagesize = sizeof(*p);
+ buf = kzalloc((pagesize * 3), GFP_KERNEL);
+ if (!buf)
return -ENOMEM;

ret = nand_read_param_page_op(chip, 0, NULL, 0);
@@ -5113,7 +5117,8 @@ 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);
+ p = (struct nand_onfi_params *)&buf[i*pagesize];
+ ret = nand_read_data_op(chip, p, pagesize, true);
if (ret) {
ret = 0;
goto free_onfi_param_page;
@@ -5126,8 +5131,27 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
}

if (i == 3) {
- pr_err("Could not find valid ONFI parameter page; aborting\n");
- goto free_onfi_param_page;
+ int j, k, l;
+ u8 v, m;
+
+ pr_err("Could not find valid ONFI parameter page\n");
+ pr_info("Recover ONFI params with bit-wise majority\n");
+ for (j = 0; j < pagesize; j++) {
+ v = 0;
+ for (k = 0; k < 8; k++) {
+ m = 0;
+ for (l = 0; l < 3; l++)
+ m += GET_BIT(k, buf[l*pagesize + j]);
+ if (m > 1)
+ v |= BIT(k);
+ }
+ ((u8 *)p)[j] = v;
+ }
+ if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)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

Thanks.
Jane

> -----Original Message-----
> From: Boris Brezillon [mailto:boris.brezillon@xxxxxxxxxxx]
> Sent: Wednesday, May 02, 2018 3:32 AM
> To: Wan, Jane (Nokia - US/Sunnyvale) <jane.wan@xxxxxxxxx>
> Cc: dwmw2@xxxxxxxxxxxxx; computersforpeace@xxxxxxxxx; Bos, Ties (Nokia -
> US/Sunnyvale) <ties.bos@xxxxxxxxx>; linux-mtd@xxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH 2/2] Use bit-wise majority to recover the contents of ONFI
> parameter
>
> On Wed, 2 May 2018 12:25:45 +0200
> Boris Brezillon <boris.brezillon@xxxxxxxxxxx> wrote:
>
> > Hi Jane,
> >
> > On Thu, 26 Apr 2018 17:19:56 -0700
> > Jane Wan <Jane.Wan@xxxxxxxxx> wrote:
> >
> > > Signed-off-by: Jane Wan <Jane.Wan@xxxxxxxxx>
> > > ---
> > > 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.

Attachment: 0002-mtd-rawnand-fsl_ifc-use-bit-wise-majority-to-recover.patch
Description: 0002-mtd-rawnand-fsl_ifc-use-bit-wise-majority-to-recover.patch