[PATCH v3 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to recover the contents of ONFI parameter

[Wan, Jane (Nokia - US/Sunnyvale)]

Hi Boris,

I've sent v4 of the patches based on the comments.

Thanks.
Jane

> -----Original Message-----
> From: Boris Brezillon [mailto:boris.brezillon at bootlin.com]
> Sent: Tuesday, May 08, 2018 2:09 AM
> To: Wan, Jane (Nokia - US/Sunnyvale) <jane.wan at nokia.com>
> Cc: miquel.raynal at bootlin.com; dwmw2 at infradead.org;
> computersforpeace at gmail.com; richard at nod.at; marek.vasut at gmail.com;
> yamada.masahiro at socionext.com; prabhakar.kushwaha at nxp.com;
> shawnguo at kernel.org; jagdish.gediya at nxp.com;
> shreeya.patel23498 at gmail.com; linux-mtd at lists.infradead.org; linux-
> kernel at vger.kernel.org; Bos, Ties (Nokia - US/Sunnyvale) <ties.bos at nokia.com>
> Subject: Re: [PATCH v3 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to
> recover the contents of ONFI parameter
> 
> On Mon,  7 May 2018 09:34:15 -0700
> Jane Wan <Jane.Wan at 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 at nokia.com>
> 
> I never received patch 1 of this series. When you fix something in a commit,
> please resend the whole patchset, even if other patches haven't changed.

 [Jane] Thanks for the info.  I've sent both patches on v4.

> 
> > ---
> >  drivers/mtd/nand/raw/nand_base.c |   41
> ++++++++++++++++++++++++++++++--------
> >  1 file changed, 33 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/mtd/nand/raw/nand_base.c
> > b/drivers/mtd/nand/raw/nand_base.c
> > index 72f3a89..48f2dec 100644
> > --- a/drivers/mtd/nand/raw/nand_base.c
> > +++ b/drivers/mtd/nand/raw/nand_base.c
> > @@ -5086,15 +5086,18 @@ 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.
> >   */
> >  static int nand_flash_detect_onfi(struct nand_chip *chip)  {
> >  	struct mtd_info *mtd = nand_to_mtd(chip);
> > -	struct nand_onfi_params *p;
> > +	struct nand_onfi_params *p = NULL;
> >  	char id[4];
> > -	int i, ret, val;
> > +	int i, ret, val, pagesize;
> > +	u8 *buf = NULL;
> >
> >  	/* 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);
> 
> Not sure why you have to add a new buf variable here, and pagesize is not
> needed either, just use sizeof(*p) directly.

[Jane] Removed buf in v4.

> 
> > +	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;
> > +		}
> 
> Can you move the bit-wise majority code in a separate function?

[Jane] Done as suggested in v4.

> 
> > +		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 */
> > @@ -5220,7 +5244,8 @@ static int nand_flash_detect_onfi(struct nand_chip
> *chip)
> >  	       sizeof(p->vendor));
> >
> >  free_onfi_param_page:
> > -	kfree(p);
> > +	if (buf != NULL)
> > +		kfree(buf);
> 
> kfree() already handles the buf == NULL case, no need to check it here.

[Jane]  Removed the check.  Thanks.
 
> 
> >  	return ret;
> >  }
> >