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Date: Mon, 28 May 2018 09:09:31 +0200
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Abhishek Sahu <absahu@codeaurora.org>
Cc: Boris Brezillon <boris.brezillon@bootlin.com>, David Woodhouse
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 <andy.gross@linaro.org>, Archit Taneja <architt@codeaurora.org>
Subject: Re: [PATCH v3 13/16] mtd: rawnand: qcom: minor code reorganization
 for bad block check
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Hi Abhishek,

On Mon, 28 May 2018 11:46:47 +0530, Abhishek Sahu
<absahu@codeaurora.org> wrote:

> On 2018-05-26 14:28, Miquel Raynal wrote:
> > Hi Abhishek, =20
> > > >> @@ -2141,12 +2127,10 @@ static int qcom_nandc_block_bad(struct >> =
mtd_info *mtd, loff_t ofs) =20
> >>  		goto err;
> >>  	} =20
> >> >> -	bbpos =3D mtd->writesize - host->cw_size * (ecc->steps - 1); =20
> >> -
> >> -	bad =3D nandc->data_buffer[bbpos] !=3D 0xff;
> >> +	bad =3D bbm_bytes_buf[0] !=3D 0xff;
> > > BTW, as there are host->bbm_size bytes that can inform on the block =
=20
> > state, don't we need to check all of them?
> >  =20
>   We are checking all of them.
>   host->bbm_size will be either 1 (for NAND_BUSWIDTH_8) or
>   2 (for NAND_BUSWIDTH_16).
>=20
>   https://elixir.bootlin.com/linux/v4.17-rc7/source/drivers/mtd/nand/raw/=
qcom_nandc.c#L2347
>=20
>   Thanks,
>   Abhishek
>=20
> >> >>  	if (chip->options & NAND_BUSWIDTH_16) =20
> >> -		bad =3D bad || (nandc->data_buffer[bbpos + 1] !=3D 0xff);
> >> +		bad =3D bad || (bbm_bytes_buf[1] !=3D 0xff);

As told in my previous reply, I missed the above line.

However, after checking the code of the core (nand_base.c) I wonder if
it is useful to check for the second byte.

And if you look at the core's implementation you'll see that the offset
is not always 0 in the OOB but maybe 5 for small page NAND chips.

Please have a look to the generic implementation and tell me why this
is really needed?

Thanks,
Miqu=C3=A8l