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SubjectRe: [PATCH 2/2] mtd: spi-nor: Add support for flash reset
Hi,

Am 2022-08-29 11:05, schrieb Sai Krishna Potthuri:
> 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@amd.com>
> ---
> drivers/mtd/spi-nor/core.c | 50 +++++++++++++++++++++++++++++++++++---
> 1 file changed, 46 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index f2c64006f8d7..d4703ff69ad0 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -2401,12 +2401,8 @@ static void spi_nor_no_sfdp_init_params(struct
> spi_nor *nor)
> */
> static void spi_nor_init_flags(struct spi_nor *nor)
> {
> - struct device_node *np = spi_nor_get_flash_node(nor);
> const u16 flags = nor->info->flags;
>
> - if (of_property_read_bool(np, "broken-flash-reset"))
> - nor->flags |= SNOR_F_BROKEN_RESET;
> -
> if (flags & SPI_NOR_SWP_IS_VOLATILE)
> nor->flags |= SNOR_F_SWP_IS_VOLATILE;
>
> @@ -2933,9 +2929,47 @@ 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;
> + int ret;
> +
> + reset = devm_gpiod_get_optional(nor->dev, "reset", GPIOD_ASIS);

devm_gpiod_get_optional(nor->dev, "reset", GPIOD_OUT_HIGH);

> + if (IS_ERR_OR_NULL(reset))
> + return PTR_ERR_OR_ZERO(reset);
> +
> + /* Set the direction as output and enable the output */
> + ret = gpiod_direction_output(reset, 1);

Not necessary then.

> + if (ret)
> + return ret;
> +
> + /*
> + * Experimental Minimum Chip select high to Reset delay value
> + * based on the flash device spec.
> + */

Which flash device spec?

> + usleep_range(1, 5);
> + gpiod_set_value(reset, 0);

Mh, is your logic inverted here? If I read the code correctly,
you should use a value of 1 to take the device into reset. The
device tree should then have a flag "active low", which will
invert the value here. Also please use the cansleep() variant.

> + /*
> + * Experimental Minimum Reset pulse width value based on the
> + * flash device spec.
> + */
> + usleep_range(10, 15);
> + gpiod_set_value(reset, 1);
> +
> + /*
> + * Experimental Minimum Reset recovery delay value based on the
> + * flash device spec.
> + */
> + usleep_range(35, 40);
> +
> + return 0;
> +}
> +
> int spi_nor_scan(struct spi_nor *nor, const char *name,
> const struct spi_nor_hwcaps *hwcaps)
> {
> + struct device_node *np = spi_nor_get_flash_node(nor);
> const struct flash_info *info;
> struct device *dev = nor->dev;
> struct mtd_info *mtd = &nor->mtd;
> @@ -2965,6 +2999,14 @@ int spi_nor_scan(struct spi_nor *nor, const char
> *name,
> if (!nor->bouncebuf)
> return -ENOMEM;
>
> + if (of_property_read_bool(np, "broken-flash-reset")) {
> + nor->flags |= SNOR_F_BROKEN_RESET;
> + } else {
> + ret = spi_nor_hw_reset(nor);
> + if (ret)
> + return ret;
> + }

This should be done unconditionally, no? Even if the reset
pin is broken, we know we have one (otherwise the device
tree would be broken) and we can do a reset in any case.

Also, which tree are you using? That was moved into
spi_nor_init_flags() some time ago. Please rebase to latest
spi-next.

-michael

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

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