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Message-ID: <VI1PR07MB161596607D2DF2CE52DF01E881980@VI1PR07MB1615.eurprd07.prod.outlook.com>
Date: Thu, 10 May 2018 21:37:19 +0000
From: "Wan, Jane (Nokia - US/Sunnyvale)" <jane.wan@...ia.com>
To: Boris Brezillon <boris.brezillon@...tlin.com>
CC: "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
"dwmw2@...radead.org" <dwmw2@...radead.org>,
"computersforpeace@...il.com" <computersforpeace@...il.com>,
"richard@....at" <richard@....at>,
"marek.vasut@...il.com" <marek.vasut@...il.com>,
"yamada.masahiro@...ionext.com" <yamada.masahiro@...ionext.com>,
"prabhakar.kushwaha@....com" <prabhakar.kushwaha@....com>,
"shawnguo@...nel.org" <shawnguo@...nel.org>,
"jagdish.gediya@....com" <jagdish.gediya@....com>,
"shreeya.patel23498@...il.com" <shreeya.patel23498@...il.com>,
"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Bos, Ties (Nokia - US/Sunnyvale)" <ties.bos@...ia.com>
Subject: RE: [PATCH v5 2/2] mtd: rawnand: use bit-wise majority to recover the
contents of ONFI parameter
Hi Boris,
I've sent v6 of the patch based on your comments.
Thanks.
Jane
> -----Original Message-----
> From: Boris Brezillon [mailto:boris.brezillon@...tlin.com]
> Sent: Thursday, May 10, 2018 5:03 AM
> To: Wan, Jane (Nokia - US/Sunnyvale) <jane.wan@...ia.com>
> Cc: miquel.raynal@...tlin.com; dwmw2@...radead.org;
> computersforpeace@...il.com; richard@....at; marek.vasut@...il.com;
> yamada.masahiro@...ionext.com; prabhakar.kushwaha@....com;
> shawnguo@...nel.org; jagdish.gediya@....com;
> shreeya.patel23498@...il.com; linux-mtd@...ts.infradead.org; linux-
> kernel@...r.kernel.org; Bos, Ties (Nokia - US/Sunnyvale) <ties.bos@...ia.com>
> Subject: Re: [PATCH v5 2/2] mtd: rawnand: use bit-wise majority to recover the
> contents of ONFI parameter
>
> 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 Subject prefix should be "[PATCH v5] ...", the 2/2 is no longer valid since you only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@...ia.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@...ia.com>
> > ---
>
> There should be a changelog here describing what has changed in each version
> of the patch.
[Jane] Added the changelogs in v6.
>
> > 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.
[Jane] Removed.
>
> > +
> > +/*
> > + * 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)
[Jane] changed as above in v6.
>
> > +{
> > + 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.
[Jane] Changed as you suggested to support non-contiguous srcbufs.
>
> > + 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.
[Jane] changed the variables to cnt and val in v6. The "m" was for majority, now changed to cnt (counts for 1s).
>
> > + 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)
[Jane] Changed as suggested in v6. Thanks.
>
> > + 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))
[Jane] Changed in v6. Thanks.
>
> > + 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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