linux-kernel - Re: [PATCH v2 01/14] mtd: rawnand: helper function for setting up ECC parameters

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Message-ID: <20180507101646.3df649b0@bbrezillon>
Date:   Mon, 7 May 2018 10:16:46 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Abhishek Sahu <absahu@...eaurora.org>
Cc:     Archit Taneja <architt@...eaurora.org>,
        Richard Weinberger <richard@....at>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Marek Vasut <marek.vasut@...il.com>,
        linux-mtd@...ts.infradead.org,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Andy Gross <andy.gross@...aro.org>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH v2 01/14] mtd: rawnand: helper function for setting up
 ECC parameters

On Thu,  3 May 2018 17:50:28 +0530
Abhishek Sahu <absahu@...eaurora.org> wrote:

> commit 2c8f8afa7f92 ("mtd: nand: add generic helpers to check,
> match, maximize ECC settings") provides generic helpers which
> drivers can use for setting up ECC parameters.
> 
> Since same board can have different ECC strength nand chips so
> following is the logic for setting up ECC strength and ECC step
> size, which can be used by most of the drivers.
> 
> 1. If both ECC step size and ECC strength are already set
>    (usually by DT) then just check whether this setting
>    is supported by NAND controller.
> 2. If NAND_ECC_MAXIMIZE is set, then select maximum ECC strength
>    supported by NAND controller.
> 3. Otherwise, try to match the ECC step size and ECC strength closest
>    to the chip's requirement. If available OOB size can't fit the chip
>    requirement then select maximum ECC strength which can be fit with
>    available OOB size with warning.
> 
> This patch introduces nand_ecc_param_setup function which calls the
> required helper functions for the above logic. The drivers can use
> this single function instead of calling the 3 helper functions
> individually.
> 
> CC: Masahiro Yamada <yamada.masahiro@...ionext.com>
> Signed-off-by: Abhishek Sahu <absahu@...eaurora.org>
> ---
> * Changes from v1:
> 
>   NEW PATCH
> 
>  drivers/mtd/nand/raw/nand_base.c | 42 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/mtd/rawnand.h      |  3 +++
>  2 files changed, 45 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 72f3a89..dd7a984 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -6249,6 +6249,48 @@ int nand_maximize_ecc(struct nand_chip *chip,
>  }
>  EXPORT_SYMBOL_GPL(nand_maximize_ecc);
>  
> +/**
> + * nand_ecc_param_setup - Set the ECC strength and ECC step size
> + * @chip: nand chip info structure
> + * @caps: ECC engine caps info structure
> + * @oobavail: OOB size that the ECC engine can use
> + *
> + * Choose the ECC strength according to following logic
> + *
> + * 1. If both ECC step size and ECC strength are already set (usually by DT)
> + *    then check if it is supported by this controller.
> + * 2. If NAND_ECC_MAXIMIZE is set, then select maximum ECC strength.
> + * 3. Otherwise, try to match the ECC step size and ECC strength closest
> + *    to the chip's requirement. If available OOB size can't fit the chip
> + *    requirement then fallback to the maximum ECC step size and ECC strength
> + *    and print the warning.
> + *
> + * On success, the chosen ECC settings are set.
> + */
> +int nand_ecc_param_setup(struct nand_chip *chip,
> +			 const struct nand_ecc_caps *caps, int oobavail)

Can we rename this function "nand_ecc_choose_conf()".