linux-kernel - Re: [PATCH v2 5/9] mtd: nand: atmel: Report PMECC failures as errors

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Date:   Mon, 18 Sep 2017 12:00:51 +0200
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Romain Izard <romain.izard.pro@...il.com>
Cc:     Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Wenyou Yang <wenyou.yang@...el.com>,
        Josh Wu <rainyfeeling@...look.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        Thierry Reding <thierry.reding@...il.com>,
        Richard Genoud <richard.genoud@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        linux-pwm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org,
        linux-serial@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 5/9] mtd: nand: atmel: Report PMECC failures as
 errors

Hi Romain,

On Fri, 15 Sep 2017 16:04:07 +0200
Romain Izard <romain.izard.pro@...il.com> wrote:

> It is not normal for the PMECC to fail when trying to fix ECC errors.
> Report these cases as errors.

I'm not sure we want to have ECC error messages at this level. ECC
errors are rather unusual but not impossible, and sometimes it's even
not a real error (I'm thinking of bitflips in erased pages for
example, which are not necessarily detected/fixed in hardware).

If we decide to print error messages when unfixable bitflips are
detected, it should be done in the nand-controller driver (somewhere
along those lines [1]).

Regards,

Boris

[1]http://elixir.free-electrons.com/linux/latest/source/drivers/mtd/nand/atmel/nand-controller.c#L827

> 
> Signed-off-by: Romain Izard <romain.izard.pro@...il.com>
> ---
>  drivers/mtd/nand/atmel/pmecc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/nand/atmel/pmecc.c b/drivers/mtd/nand/atmel/pmecc.c
> index 8d1208f38025..2a23f1ff945f 100644
> --- a/drivers/mtd/nand/atmel/pmecc.c
> +++ b/drivers/mtd/nand/atmel/pmecc.c
> @@ -687,6 +687,8 @@ static int atmel_pmecc_err_location(struct atmel_pmecc_user *user)
>  	 * Number of roots does not match the degree of smu
>  	 * unable to correct error.
>  	 */
> +	dev_err(pmecc->dev,
> +		"PMECC: Impossible to calculate error location.\n");
>  	return -EBADMSG;
>  }
>  
> @@ -729,7 +731,7 @@ int atmel_pmecc_correct_sector(struct atmel_pmecc_user *user, int sector,
>  			ptr = ecc + byte - sectorsize;
>  			area = "ECC";
>  		} else {
> -			dev_dbg(pmecc->dev,
> +			dev_err(pmecc->dev,
>  				"Invalid errpos value (%d, max is %d)\n",
>  				errpos, (sectorsize + eccbytes) * 8);
>  			return -EINVAL;