Re: [PATCH v2 07/36] mtd: rawnand: Avoid a typedef

From: Boris Brezillon <boris.brezillon@collabora.com>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Mason Yang <masonccyang@mxic.com.tw>, Vignesh R <vigneshr@ti.com>,
	Tudor Ambarus <Tudor.Ambarus@microchip.com>,
	Julien Su <juliensu@mxic.com.tw>,
	Richard Weinberger <richard@nod.at>,
	Boris Brezillon <bbrezillon@kernel.org>,
	Schrempf Frieder <frieder.schrempf@kontron.de>,
	Paul Cercueil <paul@crapouillou.net>,
	Marek Vasut <marek.vasut@gmail.com>,
	linux-mtd@lists.infradead.org,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Brian Norris <computersforpeace@gmail.com>,
	David Woodhouse <dwmw2@infradead.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 07/36] mtd: rawnand: Avoid a typedef
Date: Sun, 31 Mar 2019 13:55:13 +0200	[thread overview]
Message-ID: <20190331135513.59257c1d@collabora.com> (raw)
In-Reply-To: <20190304222841.13899-8-miquel.raynal@bootlin.com>

On Mon,  4 Mar 2019 23:28:12 +0100
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> In new code, the use of typedef is discouraged. Before moving this
> section out of the raw NAND base, let's switch the nand_ecc_modes_t
> type into a regular nand_ecc_mode enumeration.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/mtd/nand/raw/nand_base.c               | 4 ++--
>  include/linux/mtd/rawnand.h                    | 6 +++---
>  include/linux/platform_data/mtd-davinci.h      | 2 +-
>  include/linux/platform_data/mtd-nand-s3c2410.h | 2 +-
>  4 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index e14f02a01efd..05174c6a3099 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -4881,8 +4881,8 @@ static int of_get_nand_ecc_mode(struct device_node *np)
>  
>  	/*
>  	 * For backward compatibility we support few obsoleted values that don't
> -	 * have their mappings into nand_ecc_modes_t anymore (they were merged
> -	 * with other enums).
> +	 * have their mappings into the nand_ecc_mode enum anymore (they were
> +	 * merged with other enums).
>  	 */
>  	if (!strcasecmp(pm, "soft_bch"))
>  		return NAND_ECC_SOFT;
> diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
> index 14748183508b..c5bf6bb49329 100644
> --- a/include/linux/mtd/rawnand.h
> +++ b/include/linux/mtd/rawnand.h
> @@ -87,14 +87,14 @@ struct nand_chip;
>  /*
>   * Constants for ECC_MODES
>   */
> -typedef enum {
> +enum nand_ecc_mode {
>  	NAND_ECC_NONE,
>  	NAND_ECC_SOFT,
>  	NAND_ECC_HW,
>  	NAND_ECC_HW_SYNDROME,
>  	NAND_ECC_HW_OOB_FIRST,
>  	NAND_ECC_ON_DIE,
> -} nand_ecc_modes_t;
> +};

Hm, I'm really not a big fan of this enum because it's mixing 2
different concepts: the type of ECC engine to use (on-die,
hw-controller-side, software, no-ECC) and the layout of
ECC/FREE bytes (_SYNDROME, _OOB_FIRST).

I'd recommend creating a nand_ecc_engine_type enum:

enum nand_ecc_engine_type {
	NAND_NO_ECC_ENGINE,
	NAND_SOFT_ECC_ENGINE,
	NAND_HW_ECC_ENGINE,
	NAND_ON_DIE_ECC_ENGINE,
};

and then convert the raw NAND layer to this enum when the time comes.

>  
>  enum nand_ecc_algo {
>  	NAND_ECC_UNKNOWN,
> @@ -340,7 +340,7 @@ static const struct nand_ecc_caps __name = {			\
>   * @write_oob:	function to write chip OOB data
>   */
>  struct nand_ecc_ctrl {
> -	nand_ecc_modes_t mode;
> +	enum nand_ecc_mode mode;
>  	enum nand_ecc_algo algo;
>  	int steps;
>  	int size;
> diff --git a/include/linux/platform_data/mtd-davinci.h b/include/linux/platform_data/mtd-davinci.h
> index 1bbfa27cccb4..e7457be12b8f 100644
> --- a/include/linux/platform_data/mtd-davinci.h
> +++ b/include/linux/platform_data/mtd-davinci.h
> @@ -81,7 +81,7 @@ struct davinci_nand_pdata {		/* platform_data */
>  	 * Newer ones also support 4-bit ECC, but are awkward
>  	 * using it with large page chips.
>  	 */
> -	nand_ecc_modes_t	ecc_mode;
> +	enum nand_ecc_mode	ecc_mode;
>  	u8			ecc_bits;
>  
>  	/* e.g. NAND_BUSWIDTH_16 */
> diff --git a/include/linux/platform_data/mtd-nand-s3c2410.h b/include/linux/platform_data/mtd-nand-s3c2410.h
> index f8c553f92655..ff6501c51244 100644
> --- a/include/linux/platform_data/mtd-nand-s3c2410.h
> +++ b/include/linux/platform_data/mtd-nand-s3c2410.h
> @@ -52,7 +52,7 @@ struct s3c2410_platform_nand {
>  
>  	unsigned int	ignore_unset_ecc:1;
>  
> -	nand_ecc_modes_t	ecc_mode;
> +	enum nand_ecc_mode	ecc_mode;
>  
>  	int			nr_sets;
>  	struct s3c2410_nand_set *sets;

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