[PATCH] ath79: rb4xx-nand: fix 512 byte pages compatibility

[Bas Mevissen]

A few nitpicks:

On 2021-05-28 00:27, Sergey Ryazanov wrote:
> MikroTik boards with 512 byte NAND pages require the old YAFFS1 OOB
> layout for compatibility with the RouterBoot bootloader. The RB4xx NAND
> driver supports such OOB layout, but checks a NAND page size too early
> before the flash identification, what effectively preventing the old 
> OOB
> layout from being used.
> 
> To fix this issue, move the page size check and OOB layout 
> configuration
> to the chip attaching hook, which is specially intorduced for ECC and
> OOB tweaking.
> 
> While at it, copy a comment from the old AR71xx driver to make it 
> clear,
> why do we need this OOB layout tweaking.
> 
> Run tested with MikroTik RB411U board.
> 
> Signed-off-by: Sergey Ryazanov <ryazanov.s.a at gmail.com>
> ---
>  .../files/drivers/mtd/nand/raw/nand_rb4xx.c   | 25 ++++++++++++++++---
>  1 file changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git
> a/target/linux/ath79/files/drivers/mtd/nand/raw/nand_rb4xx.c
> b/target/linux/ath79/files/drivers/mtd/nand/raw/nand_rb4xx.c
> index 50bd69f6a4..00c65d14ae 100644
> --- a/target/linux/ath79/files/drivers/mtd/nand/raw/nand_rb4xx.c
> +++ b/target/linux/ath79/files/drivers/mtd/nand/raw/nand_rb4xx.c
> @@ -81,6 +81,23 @@ static const struct mtd_ooblayout_ops
> rb4xx_nand_ecclayout_ops = {
>  	.free = rb4xx_ooblayout_free,
>  };
> 
> +static int rb4xx_nand_attach_chip(struct nand_chip *chip)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +
> +	/*
> +	 * Now we knows flash parameters and can tweak OOB the layout for old

Rephrase to something like:
Knowing the flash parameters, we can tweak the OOB layout for old

> +	 * (usually 64MiB) flashes.
> +	 *
> +	 * We need to use the OLD Yaffs-1 OOB layout, otherwise the RB
> +	 * bootloader will not be able to find the kernel that we load.
> +	 */
> +	if (mtd->writesize == 512)
> +		mtd_set_ooblayout(mtd, &rb4xx_nand_ecclayout_ops);
> +
> +	return 0;
> +}
> +
>  static u8 rb4xx_nand_read_byte(struct nand_chip *chip)
>  {
>  	struct rb4xx_nand *nand = chip->priv;
> @@ -135,6 +152,10 @@ static int rb4xx_nand_dev_ready(struct nand_chip 
> *chip)
>  	return gpiod_get_value_cansleep(nand->rdy);
>  }
> 
> +static const struct nand_controller_ops rb4xx_nand_controller_ops = {
> +	.attach_chip = rb4xx_nand_attach_chip,

remove the ,
> +};
> +
>  static int rb4xx_nand_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -185,9 +206,6 @@ static int rb4xx_nand_probe(struct platform_device 
> *pdev)
>  	mtd->dev.parent	= dev;
>  	mtd_set_of_node(mtd, dev->of_node);
> 
> -	if (mtd->writesize == 512)
> -		mtd_set_ooblayout(mtd, &rb4xx_nand_ecclayout_ops);
> -
>  	nand->chip.ecc.mode	= NAND_ECC_SOFT;
>  	nand->chip.ecc.algo	= NAND_ECC_HAMMING;
>  	nand->chip.options	= NAND_NO_SUBPAGE_WRITE;
> @@ -199,6 +217,7 @@ static int rb4xx_nand_probe(struct platform_device 
> *pdev)
>  	nand->chip.legacy.cmd_ctrl	= rb4xx_nand_cmd_ctrl;
>  	nand->chip.legacy.dev_ready	= rb4xx_nand_dev_ready;
>  	nand->chip.legacy.chip_delay	= 25;
> +	nand->chip.legacy.dummy_controller.ops = &rb4xx_nand_controller_ops;

Fix indentation for all nand->something assignments to line up the = 
sign

> 
>  	ret = nand_scan(&nand->chip, 1);
>  	if (ret)