On Thu, Jan 30, 2020 at 12:57 AM Masahiro Yamada
<yamada.masah...@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.masah...@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
