Re: [PATCH] mtd: rawnand: denali_dt: Add support for configuring SPARE_AREA_SKIP_BYTES

[<Tudor.Ambarus@xxxxxxxxxxxxx>]

Hi, Marek, Masahiro,

On 12/7/19 2:48 AM, Marek Vasut wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> The SPARE_AREA_SKIP_BYTES register is reset when the controller reset
> signal is toggled. Yet, this register must be configured to match the
> content of the NAND OOB area. The current default value is always set
> to 8 and is programmed into the hardware in case the hardware was not
> programmed before (e.g. in a bootloader) with a different value. This
> however does not work when the block is reset properly by Linux.
> 
> On Altera SoCFPGA CycloneV, ArriaV and Arria10, which are the SoCFPGA
> platforms which support booting from NAND, the SPARE_AREA_SKIP_BYTES
> value must be set to 2. On Socionext Uniphier, the value is 8. This
> patch adds support for preconfiguring the default value and handles
> the special SoCFPGA case by setting the default to 2 on all SoCFPGA
> platforms, while retaining the original behavior and default value of
> 8 on all the other platforms.
> 
> Signed-off-by: Marek Vasut <marex@xxxxxxx>
> Cc: Ley Foon Tan <ley.foon.tan@xxxxxxxxx>
> Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> Cc: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> Cc: Richard Weinberger <richard@xxxxxx>
> Cc: Vignesh Raghavendra <vigneshr@xxxxxx>
> To: linux-mtd@xxxxxxxxxxxxxxxxxxx
> ---
>  drivers/mtd/nand/raw/denali.c    | 13 ++++++++++---
>  drivers/mtd/nand/raw/denali_dt.c |  6 ++++++
>  2 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c
> index 3102ddbd8abdb..b6c463d021677 100644
> --- a/drivers/mtd/nand/raw/denali.c
> +++ b/drivers/mtd/nand/raw/denali.c
> @@ -1302,14 +1302,21 @@ int denali_init(struct denali_controller *denali)
> 
>         /*
>          * Set how many bytes should be skipped before writing data in OOB.
> +        * If a non-zero value has already been configured, update it in HW.
>          * If a non-zero value has already been set (by firmware or something),
>          * just use it. Otherwise, set the driver's default.
>          */
> -       denali->oob_skip_bytes = ioread32(denali->reg + SPARE_AREA_SKIP_BYTES);
> -       if (!denali->oob_skip_bytes) {
> -               denali->oob_skip_bytes = DENALI_DEFAULT_OOB_SKIP_BYTES;
> +       if (denali->oob_skip_bytes) {
>                 iowrite32(denali->oob_skip_bytes,
>                           denali->reg + SPARE_AREA_SKIP_BYTES);
> +       } else {
> +               denali->oob_skip_bytes =
> +                       ioread32(denali->reg + SPARE_AREA_SKIP_BYTES);
> +               if (!denali->oob_skip_bytes) {
> +                       denali->oob_skip_bytes = DENALI_DEFAULT_OOB_SKIP_BYTES;
> +                       iowrite32(denali->oob_skip_bytes,
> +                                 denali->reg + SPARE_AREA_SKIP_BYTES);
> +               }
>         }
> 
>         iowrite32(0, denali->reg + TRANSFER_SPARE_REG);
> diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
> index 5e14836f6bd5a..34c7c553f3412 100644
> --- a/drivers/mtd/nand/raw/denali_dt.c
> +++ b/drivers/mtd/nand/raw/denali_dt.c
> @@ -27,6 +27,7 @@ struct denali_dt {
>  struct denali_dt_data {
>         unsigned int revision;
>         unsigned int caps;
> +       unsigned int oob_skip_bytes;
>         const struct nand_ecc_caps *ecc_caps;
>  };
> 
> @@ -34,6 +35,7 @@ NAND_ECC_CAPS_SINGLE(denali_socfpga_ecc_caps, denali_calc_ecc_bytes,
>                      512, 8, 15);
>  static const struct denali_dt_data denali_socfpga_data = {
>         .caps = DENALI_CAP_HW_ECC_FIXUP,
> +       .oob_skip_bytes = 2,
>         .ecc_caps = &denali_socfpga_ecc_caps,
>  };
> 
> @@ -42,6 +44,7 @@ NAND_ECC_CAPS_SINGLE(denali_uniphier_v5a_ecc_caps, denali_calc_ecc_bytes,
>  static const struct denali_dt_data denali_uniphier_v5a_data = {
>         .caps = DENALI_CAP_HW_ECC_FIXUP |
>                 DENALI_CAP_DMA_64BIT,
> +       .oob_skip_bytes = 8,
>         .ecc_caps = &denali_uniphier_v5a_ecc_caps,
>  };
> 
> @@ -51,6 +54,7 @@ static const struct denali_dt_data denali_uniphier_v5b_data = {
>         .revision = 0x0501,
>         .caps = DENALI_CAP_HW_ECC_FIXUP |
>                 DENALI_CAP_DMA_64BIT,
> +       .oob_skip_bytes = 8,
>         .ecc_caps = &denali_uniphier_v5b_ecc_caps,
>  };
> 
> @@ -209,6 +213,8 @@ static int denali_dt_probe(struct platform_device *pdev)
>         denali->clk_rate = clk_get_rate(dt->clk);
>         denali->clk_x_rate = clk_get_rate(dt->clk_x);
> 
> +       denali->oob_skip_bytes = data->oob_skip_bytes;
> +

This indeed should be moved immediately after getting of_device_get_match_data.
I share Marek's opinion that what Masahiro have identified worths a separate
patch. Ideally we should fix one thing per patch. With this moved immediately
after of_device_get_match_data() one can add:

Reviewed-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>

Cheers,
ta
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