linux-kernel - Re: [PATCH] mtd: nand: fix lack of oob layout when using no ecc

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Message-ID: <20170710133548.1d151b15@xps13>
Date:   Mon, 10 Jul 2017 13:35:48 +0200
From:   Miquel RAYNAL <miquel.raynal@...e-electrons.com>
To:     Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:     Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: nand: fix lack of oob layout when using no ecc

On Mon, 10 Jul 2017 13:27:13 +0200
Boris Brezillon <boris.brezillon@...e-electrons.com> wrote:

> On Mon, 10 Jul 2017 12:37:26 +0200
> Miquel Raynal <miquel.raynal@...e-electrons.com> wrote:
> 
> > Fix nand core lack of OOB layout when:
> > - the NFC driver does not provide any OOB layout,
> > - ECC operations are disabled (using NAND_ECC_NONE).
> > Using this configuration leads to a crash during the probe.
> > 
> > Add layout functions for small and large pages with mainly free
> > bytes plus reserved space for bad block markers.
> > 
> > Check the configuration and eventually assign this OOB layout in
> > nand_scan_tail().
> > 
> > Bad block markers position was extracted from the existing OOB
> > layouts by assigning as free all the bytes marked as ECC.
> > 
> > Signed-off-by: Miquel Raynal <miquel.raynal@...e-electrons.com>
> > ---
> >  drivers/mtd/nand/nand_base.c | 75
> > +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 74
> > insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/mtd/nand/nand_base.c
> > b/drivers/mtd/nand/nand_base.c index c5221795a1e8..28ff58e4385f
> > 100644 --- a/drivers/mtd/nand/nand_base.c
> > +++ b/drivers/mtd/nand/nand_base.c
> > @@ -53,7 +53,45 @@ static int nand_get_device(struct mtd_info *mtd,
> > int new_state); static int nand_do_write_oob(struct mtd_info *mtd,
> > loff_t to, struct mtd_oob_ops *ops);
> >  
> > -/* Define default oob placement schemes for large and small page
> > devices */ +/*
> > + * Define default OOB placement schemes for:
> > + *   - no ECC or software ECC
> > + *   - small or large page devices
> > + */
> > +static int nand_ooblayout_ecc_sp_bbm_only(struct mtd_info *mtd,
> > int section,
> > +					  struct mtd_oob_region
> > *oobregion)  
> 
> Can you suffix it with _no_ecc instead of _bbm_only?

Sure, I will send a v2.

> 
> Looks good otherwise.
> 
> > +{
> > +	return -ERANGE;
> > +}
> > +
> > +static int nand_ooblayout_free_sp_bbm_only(struct mtd_info *mtd,
> > int section,
> > +					   struct mtd_oob_region
> > *oobregion) +{
> > +	if (section > 1)
> > +		return -ERANGE;
> > +
> > +	if (!section) {
> > +		if (mtd->oobsize == 16) {
> > +			oobregion->offset = 0;
> > +			oobregion->length = 4;
> > +		} else {
> > +			oobregion->offset = 0;
> > +			oobregion->length = 5;
> > +		}
> > +	} else {
> > +		oobregion->offset = 6;
> > +		oobregion->length = mtd->oobsize -
> > oobregion->offset;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +const struct mtd_ooblayout_ops nand_ooblayout_sp_bbm_only_ops = {
> > +	.ecc = nand_ooblayout_ecc_sp_bbm_only,
> > +	.free = nand_ooblayout_free_sp_bbm_only,
> > +};
> > +EXPORT_SYMBOL_GPL(nand_ooblayout_sp_bbm_only_ops);
> > +
> >  static int nand_ooblayout_ecc_sp(struct mtd_info *mtd, int section,
> >  				 struct mtd_oob_region *oobregion)
> >  {
> > @@ -109,6 +147,30 @@ const struct mtd_ooblayout_ops
> > nand_ooblayout_sp_ops = { };
> >  EXPORT_SYMBOL_GPL(nand_ooblayout_sp_ops);
> >  
> > +static int nand_ooblayout_ecc_lp_bbm_only(struct mtd_info *mtd,
> > int section,
> > +					  struct mtd_oob_region
> > *oobregion) +{
> > +	return -ERANGE;
> > +}
> > +
> > +static int nand_ooblayout_free_lp_bbm_only(struct mtd_info *mtd,
> > int section,
> > +					   struct mtd_oob_region
> > *oobregion) +{
> > +	if (section)
> > +		return -ERANGE;
> > +
> > +	oobregion->offset = 2;
> > +	oobregion->length = mtd->oobsize - oobregion->offset;
> > +
> > +	return 0;
> > +}
> > +
> > +const struct mtd_ooblayout_ops nand_ooblayout_lp_bbm_only_ops = {
> > +	.ecc = nand_ooblayout_ecc_lp_bbm_only,
> > +	.free = nand_ooblayout_free_lp_bbm_only,
> > +};
> > +EXPORT_SYMBOL_GPL(nand_ooblayout_lp_bbm_only_ops);
> > +
> >  static int nand_ooblayout_ecc_lp(struct mtd_info *mtd, int section,
> >  				 struct mtd_oob_region *oobregion)
> >  {
> > @@ -4635,6 +4697,17 @@ int nand_scan_tail(struct mtd_info *mtd)
> >  	chip->oob_poi = chip->buffers->databuf + mtd->writesize;
> >  
> >  	/*
> > +	 * When using ECC_NONE, ooblayout must only reserve space
> > for bad block
> > +	 * markers.
> > +	 */
> > +	if (!mtd->ooblayout && ecc->mode == NAND_ECC_NONE) {
> > +		if (mtd->writesize <= 512)
> > +			mtd_set_ooblayout(mtd,
> > &nand_ooblayout_sp_bbm_only_ops);
> > +		else
> > +			mtd_set_ooblayout(mtd,
> > &nand_ooblayout_lp_bbm_only_ops);
> > +	}
> > +
> > +	/*
> >  	 * If no default placement scheme is given, select an
> > appropriate one. */
> >  	if (!mtd->ooblayout &&  
>