linux-kernel - Re: [PATCH 13/39] mtd: nand: denali: increment ecc

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Date:   Fri, 2 Dec 2016 13:28:23 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:     linux-mtd@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Brian Norris <computersforpeace@...il.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>
Subject: Re: [PATCH 13/39] mtd: nand: denali: increment ecc_stats->corrected

Hi Boris,

2016-11-28 0:31 GMT+09:00 Boris Brezillon <boris.brezillon@...e-electrons.com>:
> On Sun, 27 Nov 2016 03:05:59 +0900
> Masahiro Yamada <yamada.masahiro@...ionext.com> wrote:
>
>> Update the number of corrected bit flips when read_page() succeeds.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
>> ---
>>
>>  drivers/mtd/nand/denali.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
>> index a6445d9..4cc8945 100644
>> --- a/drivers/mtd/nand/denali.c
>> +++ b/drivers/mtd/nand/denali.c
>> @@ -1162,6 +1162,9 @@ static int denali_read_page(struct mtd_info *mtd, struct nand_chip *chip,
>>                       mtd->ecc_stats.failed++;
>>               return 0;
>>       }
>> +
>> +     mtd->ecc_stats.corrected += max_bitflips;
>
> First of all, ecc_stats.corrected should contain the total number of
> bitflips detected on the MTD device, here you're just adding the
> maximum number of bitflips per ECC chunk for the current page, which is
> slightly different.
>
> Then, ecc_stats.corrected seems to be properly updated in handle_ecc()
> [1], so I see no reason to do it here.
>

You are right.

This patch is completely wrong, so I will drop it in v2.



-- 
Best Regards
Masahiro Yamada