linux-kernel - Re: [PATCH v2 12/53] mtd: nand: denali: support HW_ECC

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Message-ID: <20170322221216.26539147@bbrezillon>
Date:   Wed, 22 Mar 2017 22:12:16 +0100
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-mtd@...ts.infradead.org, laurent.monat@...uantique.com,
        thorsten.christiansson@...uantique.com,
        Enrico Jorns <ejo@...gutronix.de>,
        Jason Roberts <jason.e.roberts@...el.com>,
        Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Brian Norris <computersforpeace@...il.com>,
        Graham Moore <grmoore@...nsource.altera.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Chuanxiao Dong <chuanxiao.dong@...el.com>,
        Jassi Brar <jaswinder.singh@...aro.org>,
        linux-kernel@...r.kernel.org, Richard Weinberger <richard@....at>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>
Subject: Re: [PATCH v2 12/53] mtd: nand: denali: support HW_ECC_FIXUP
 capability

On Wed, 22 Mar 2017 23:07:19 +0900
Masahiro Yamada <yamada.masahiro@...ionext.com> wrote:

> +static int denali_hw_ecc_fixup(struct mtd_info *mtd,
> +			       struct denali_nand_info *denali)
> +{
> +	int bank = denali->flash_bank;
> +	uint32_t ecc_cor;
> +	unsigned int max_bitflips;
> +
> +	ecc_cor = ioread32(denali->flash_reg + ECC_COR_INFO(bank));
> +	ecc_cor >>= ECC_COR_INFO__SHIFT(bank);
> +
> +	if (ecc_cor & ECC_COR_INFO__UNCOR_ERR)
> +		return -EBADMSG;

As previously mentioned, just increment ecc_stats.failed.

> +
> +	max_bitflips = ecc_cor & ECC_COR_INFO__MAX_ERRORS;
> +
> +	/*
> +	 * The register holds the maximum of the number of corrected bitflips
> +	 * per sector.  This can be returned from ecc->read_page() as-is.
> +	 * Unfortunately, we can not know the total number of corrected bits
> +	 * in the page.  mtd->ecc_stats.corrected is compromised here.
> +	 */
> +	mtd->ecc_stats.corrected += max_bitflips;
> +
> +	return max_bitflips;
> +}