[PATCH v2 1/4] mtd: rawnand: denali_dt: insert udelay() after reset deassert

[Masahiro Yamada]

On Thu, Jan 30, 2020 at 12:57 AM Masahiro Yamada
<yamada.masahiro at socionext.com> wrote:
>
> When the reset signal is de-asserted, the HW-controlled bootstrap
> starts running unless it is disabled in the SoC integration.
> It issues some commands to detect a NAND chip, and sets up registers
> automatically. Until this process finishes, software should avoid
> any register access.
>
> Without this delay function, some of UniPhier boards hangs up while
> executing nand_scan_ident(). (denali_read_byte() is blocked)
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
> ---

Applied to u-boot-uniphier.

>
> Changes in v2: None
>
>  drivers/mtd/nand/raw/denali_dt.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
> index 91d0f20aae..1afc61f876 100644
> --- a/drivers/mtd/nand/raw/denali_dt.c
> +++ b/drivers/mtd/nand/raw/denali_dt.c
> @@ -136,11 +136,19 @@ static int denali_dt_probe(struct udevice *dev)
>         }
>
>         ret = reset_get_bulk(dev, &resets);
> -       if (ret)
> +       if (ret) {
>                 dev_warn(dev, "Can't get reset: %d\n", ret);
> -       else
> +       } else {
>                 reset_deassert_bulk(&resets);
>
> +               /*
> +                * When the reset is deasserted, the initialization sequence is
> +                * kicked (bootstrap process). The driver must wait until it is
> +                * finished. Otherwise, it will result in unpredictable behavior.
> +                */
> +               udelay(200);
> +       }
> +
>         return denali_init(denali);
>  }
>
> --
> 2.17.1
>


-- 
Best Regards
Masahiro Yamada