linux-kernel - Re: [PATCH] mtd: nand: gpmi: add proper raw access support

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Message-ID: <20140911142930.GB2543@localhost.localdomain>
Date:	Thu, 11 Sep 2014 22:29:32 +0800
From:	Huang Shijie <shijie8@...il.com>
To:	Boris BREZILLON <boris.brezillon@...e-electrons.com>
Cc:	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>,
	linux-mtd@...ts.infradead.org, Huang Shijie <b32955@...escale.com>,
	Mike Voytovich <mvoytovich@...pal.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Roy Lee <roylee@...pal.com>
Subject: Re: [PATCH] mtd: nand: gpmi: add proper raw access support

On Wed, Sep 10, 2014 at 10:55:39AM +0200, Boris BREZILLON wrote:
 +static int gpmi_ecc_read_page_raw(struct mtd_info *mtd,
> +				  struct nand_chip *chip, uint8_t *buf,
> +				  int oob_required, int page)
> +{
> +	struct gpmi_nand_data *this = chip->priv;
> +	struct bch_geometry *nfc_geo = &this->bch_geometry;
> +	int eccsize = nfc_geo->ecc_chunk_size;
> +	int eccbytes = DIV_ROUND_UP(nfc_geo->ecc_strength * nfc_geo->gf_len,
> +				    8);

In actually, the ECC can be _NOT_ bytes aligned.
you should not round up to byte.

it's hard to implement this hook.

thanks
Huang Shijie
	
> +	uint8_t *oob = chip->oob_poi;
> +	int step;
> +	int column = 0;
> +	uint8_t *orig_buf = buf;
> +
> +	chip->read_buf(mtd, oob, nfc_geo->metadata_size);
> +	oob += nfc_geo->metadata_size;
> +
> +	column += nfc_geo->metadata_size;
> +	for (step = 0; step < nfc_geo->ecc_chunk_count; step++) {
> +		chip->read_buf(mtd, buf, eccsize);
> +		buf += eccsize;
> +		column += eccsize;
> +		chip->read_buf(mtd, oob, eccbytes);
> +		oob += eccbytes;
> +		column += eccbytes;
> +	}
> +
> +	if (column < mtd->writesize + mtd->oobsize)
> +		chip->read_buf(mtd, oob,
> +			       mtd->writesize + mtd->oobsize - column);
> +
> +	block_mark_swapping(this, orig_buf, chip->oob_poi);
> +
> +	return 0;
> +}
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