linux-kernel - Re: [PATCH v3 2/2] mtd: spi-nor: Add support for flash reset

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Message-ID: <7777b2fc-8c22-22dd-1ffd-dfe8a21ea0d4@microchip.com>
Date:   Mon, 3 Oct 2022 09:43:14 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <sai.krishna.potthuri@....com>, <pratyush@...nel.org>,
        <michael@...le.cc>, <miquel.raynal@...tlin.com>, <richard@....at>,
        <vigneshr@...com>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>
CC:     <devicetree@...r.kernel.org>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <saikrishna12468@...il.com>,
        <git@....com>
Subject: Re: [PATCH v3 2/2] mtd: spi-nor: Add support for flash reset

On 9/8/22 09:44, Sai Krishna Potthuri wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Add support for spi-nor flash reset via GPIO controller by reading the
> reset-gpio property. If there is a valid GPIO specifier then reset will
> be performed by asserting and deasserting the GPIO using gpiod APIs
> otherwise it will not perform any operation.
> 
> Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@....com>
> Reviewed-by: Michael Walle <michael@...le.cc>
> ---
>  drivers/mtd/spi-nor/core.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index f2c64006f8d7..a78ab9bae2be 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -2933,6 +2933,27 @@ static void spi_nor_set_mtd_info(struct spi_nor *nor)
>         mtd->_put_device = spi_nor_put_device;
>  }
> 
> +static int spi_nor_hw_reset(struct spi_nor *nor)
> +{
> +       struct gpio_desc *reset;
> +
> +       reset = devm_gpiod_get_optional(nor->dev, "reset", GPIOD_OUT_LOW);
> +       if (IS_ERR_OR_NULL(reset))
> +               return PTR_ERR_OR_ZERO(reset);
> +
> +       /*
> +        * Experimental delay values by looking at different flash device
> +        * vendors datasheets.
> +        */
> +       usleep_range(1, 5);
> +       gpiod_set_value_cansleep(reset, 1);
> +       usleep_range(100, 150);
> +       gpiod_set_value_cansleep(reset, 0);
> +       usleep_range(1000, 1200);
> +
> +       return 0;
> +}
> +
>  int spi_nor_scan(struct spi_nor *nor, const char *name,
>                  const struct spi_nor_hwcaps *hwcaps)
>  {
> @@ -2965,6 +2986,10 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
>         if (!nor->bouncebuf)
>                 return -ENOMEM;
> 
> +       ret = spi_nor_hw_reset(nor);

Should we condition the calling of this method by the absence of the "broken-flash-reset"
dt prop?

> +       if (ret)
> +               return ret;
> +
>         info = spi_nor_get_flash_info(nor, name);
>         if (IS_ERR(info))
>                 return PTR_ERR(info);
> --
> 2.17.1
> 


-- 
Cheers,
ta