linux-kernel - RE: [PATCH v2 3/3] mtd: nand: omap2: Support for hardware BCH error correction

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Message-ID: <518397C60809E147AF5323E0420B992E3EA108A9@DBDE01.ent.ti.com>
Date:	Tue, 4 Dec 2012 13:16:27 +0000
From:	"Philip, Avinash" <avinashphilip@...com>
To:	"artem.bityutskiy@...ux.intel.com" <artem.bityutskiy@...ux.intel.com>
CC:	"dwmw2@...radead.org" <dwmw2@...radead.org>,
	"Mohammed, Afzal" <afzal@...com>,
	"tony@...mide.com" <tony@...mide.com>,
	"broonie@...nsource.wolfsonmicro.com" 
	<broonie@...nsource.wolfsonmicro.com>,
	"rmk+kernel@....linux.org.uk" <rmk+kernel@....linux.org.uk>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"Nori, Sekhar" <nsekhar@...com>,
	"Hebbar, Gururaja" <gururaja.hebbar@...com>,
	"ivan.djelic@...rot.com" <ivan.djelic@...rot.com>
Subject: RE: [PATCH v2 3/3] mtd: nand: omap2: Support for hardware BCH error
 correction

On Fri, Nov 30, 2012 at 17:58:00, Artem Bityutskiy wrote:
> On Wed, 2012-10-31 at 12:38 +0530, Philip, Avinash wrote:
> > +static int erased_sector_bitflips(u_char *data, u_char *oob,
> > +               struct omap_nand_info *info)
> > +{
> > +       int flip_bits = 0, i;
> > +
> > +       for (i = 0; i < info->nand.ecc.size; i++) {
> > +               flip_bits += hweight8(~data[i]);
> > +               if (flip_bits > info->nand.ecc.strength)
> > +                       return 0;
> > +       }
> > +
> > +       for (i = 0; i < info->nand.ecc.bytes - 1; i++) {
> > +               flip_bits += hweight8(~oob[i]);
> > +               if (flip_bits > info->nand.ecc.strength)
> > +                       return 0;
> > +       }
> 
> Why do you need the second for loop?

BCH ecc is self protected & can correct bit flips in ecc bytes.
So here checking bit flips in read_ecc. I will rename variable
"oob" to "read_ecc"

Thanks
Avinash

> 
> -- 
> Best Regards,
> Artem Bityutskiy
>