[PATCH 2/2] mtd: nand: raw: denali: Wait for reset completion status

[Masahiro Yamada]

On Mon, Jun 29, 2020 at 7:12 PM Ley Foon Tan <ley.foon.tan at intel.com> wrote:
>
> Fixed delay 200us is not working in certain platforms. Change to
> poll for reset completion status to have more reliable reset process.
>
> Controller will set the rst_comp bit in intr_status register after
> controller has completed its reset and initialization process.
>
> Signed-off-by: Radu Bacrau <radu.bacrau at intel.com>
> Signed-off-by: Ley Foon Tan <ley.foon.tan at intel.com>
> ---
>  drivers/mtd/nand/raw/denali.c    | 11 +++++++++++
>  drivers/mtd/nand/raw/denali.h    |  1 +
>  drivers/mtd/nand/raw/denali_dt.c | 10 +++++++---
>  3 files changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c
> index 15e90291de09..ab91db85467d 100644
> --- a/drivers/mtd/nand/raw/denali.c
> +++ b/drivers/mtd/nand/raw/denali.c
> @@ -1220,6 +1220,17 @@ static int denali_multidev_fixup(struct denali_nand_info *denali)
>         return 0;
>  }
>
> +int denali_wait_reset_complete(struct denali_nand_info *denali)
> +{
> +       u32 irq_status;
> +
> +       irq_status = denali_wait_for_irq(denali, INTR__RST_COMP);
> +       if (!(irq_status & INTR__RST_COMP))
> +               return -EIO;
> +
> +       return 0;
> +}
> +
>  int denali_init(struct denali_nand_info *denali)
>  {
>         struct nand_chip *chip = &denali->nand;
> diff --git a/drivers/mtd/nand/raw/denali.h b/drivers/mtd/nand/raw/denali.h
> index 019deda094e5..6cd02b2e26ee 100644
> --- a/drivers/mtd/nand/raw/denali.h
> +++ b/drivers/mtd/nand/raw/denali.h
> @@ -321,6 +321,7 @@ struct denali_nand_info {
>  #define DENALI_CAP_DMA_64BIT                   BIT(1)
>
>  int denali_calc_ecc_bytes(int step_size, int strength);
> +int denali_wait_reset_complete(struct denali_nand_info *denali);
>  int denali_init(struct denali_nand_info *denali);
>
>  #endif /* __DENALI_H__ */
> diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
> index 75ad15b0758c..8a6950f8a39f 100644
> --- a/drivers/mtd/nand/raw/denali_dt.c
> +++ b/drivers/mtd/nand/raw/denali_dt.c
> @@ -154,10 +154,14 @@ static int denali_dt_probe(struct udevice *dev)
>
>                 /*
>                  * 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.
> +                * kicked. The driver must wait until it is finished. Otherwise,
> +                * it will result in unpredictable behavior.


What is your motivation for this hunk of change?
(removal of "bootstrap process")

What was wrong with the current comment block?

The term "bootstrap" appears in the
Cadence (Denali) Flash Controller User Guide.




>                  */
> -               udelay(200);
> +               ret = denali_wait_reset_complete(denali);
> +               if (ret) {
> +                       dev_err(denali->dev, "reset not completed.\n");
> +                       return ret;
> +               }
>         }
>
>         return denali_init(denali);
> --
> 2.19.0
>


I tested this patch on some of my socionext SoC boards,
and I did not see regression.

Tested-by: Masahiro Yamada <yamada.masahiro at socionext.com>


But, please note this code will diverge from the Linux code.


-- 
Best Regards
Masahiro Yamada