[U-Boot] [PATCH v1] mtd: nand: raw: allow to disable unneeded ECC layouts

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Stefan,

Stefan Agner <stefan@agner.ch> wrote on Thu,  6 Dec 2018 14:57:09 +0100:

> From: Stefan Agner <stefan.agner@toradex.com>
> 
> Each ECC layout consumes about 2984 bytes in the .data section. Allow
> to disable the default ECC layouts if a driver is known to provide its
> own ECC layout.
> 
> Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
> ---
> 
>  drivers/mtd/nand/raw/Kconfig     | 7 +++++++
>  drivers/mtd/nand/raw/nand_base.c | 4 ++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
> index 008f7b4b4b..b06c45788a 100644
> --- a/drivers/mtd/nand/raw/Kconfig
> +++ b/drivers/mtd/nand/raw/Kconfig
> @@ -9,6 +9,12 @@ config SYS_NAND_SELF_INIT
>  	  This option, if enabled, provides more flexible and linux-like
>  	  NAND initialization process.
>  
> +config SYS_NAND_DRIVER_ECC_LAYOUT
> +	bool
> +	help
> +	  Omit standard ECC layouts to safe space. Select this if your driver

s/safe/save/

> +	  is known to provide its own ECC layout.

layout*s*?

> +
>  config NAND_ATMEL
>  	bool "Support Atmel NAND controller"
>  	imply SYS_NAND_USE_FLASH_BBT
> @@ -81,6 +87,7 @@ config NAND_OMAP_ELM
>  config NAND_VF610_NFC
>  	bool "Support for Freescale NFC for VF610"
>  	select SYS_NAND_SELF_INIT
> +	select SYS_NAND_DRIVER_ECC_LAYOUT
>  	imply CMD_NAND
>  	help
>  	  Enables support for NAND Flash Controller on some Freescale
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 92daebe120..6d2ff58d86 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -47,6 +47,7 @@
>  #include <linux/errno.h>
>  
>  /* Define default oob placement schemes for large and small page devices */
> +#ifdef CONFIG_SYS_NAND_DRIVER_ECC_LAYOUT
>  static struct nand_ecclayout nand_oob_8 = {
>  	.eccbytes = 3,
>  	.eccpos = {0, 1, 2},
> @@ -89,6 +90,7 @@ static struct nand_ecclayout nand_oob_128 = {
>  		{.offset = 2,
>  		 .length = 78} }
>  };
> +#endif
>  
>  static int nand_get_device(struct mtd_info *mtd, int new_state);
>  
> @@ -4339,6 +4341,7 @@ int nand_scan_tail(struct mtd_info *mtd)
>  	 */
>  	if (!ecc->layout && (ecc->mode != NAND_ECC_SOFT_BCH)) {
>  		switch (mtd->oobsize) {
> +#ifdef CONFIG_SYS_NAND_DRIVER_ECC_LAYOUT
>  		case 8:
>  			ecc->layout = &nand_oob_8;
>  			break;
> @@ -4351,6 +4354,7 @@ int nand_scan_tail(struct mtd_info *mtd)
>  		case 128:
>  			ecc->layout = &nand_oob_128;
>  			break;
> +#endif
>  		default:
>  			pr_warn("No oob scheme defined for oobsize %d\n",
>  				   mtd->oobsize);

I don't like very much the #ifdef approach to compile-out zones in the
code. I don't have an alternative for now (maybe have the layouts in a
different file?). I would also like to hear Boris' point of view.


Thanks,
Miquèl