Re: [RESEND PATCH 1/2] mtd: spi-nor: Clear WEL bit when erase or program errors occur

[John Garry <john.garry@huawei.com>]

On 09/03/2020 10:15, Tudor.Ambarus@microchip.com wrote:
> From: Tudor Ambarus <tudor.ambarus@microchip.com>
> 
> When an Erase or Program error occurs on a spansion/cypress or a
> micron flash, the WEL bit remains set to one and should be cleared
> with a WRDI command in order to protect against inadvertent writes
> that can possible corrupt the contents of the memory.
> 
> Winbond, macronix, gd, etc., do not support the E_ERR and P_ERR bits in the
> Status Register and always clear the WEL bit regardless of the outcome
> of the erase or page program operation (ex w25q40bw, MX25L25635E).
> 
> Issue a WRDI command when erase or page program errors occur.
> 
> Reported-by: John Garry <john.garry@huawei.com>

Previously I would get this unlock complaint:

root@ubuntu:/home/john# flash_lock -l /dev/mtd0
root@ubuntu:/home/john# sudo mtd_debug erase /dev/mtd0 0xf80000 4096
[  167.458647] spi-nor spi-PRP0001:00: Erase operation failed.
[  167.464248] spi-nor spi-PRP0001:00: Attempted to modify a protected 
sector.
MEMERASE: Input/output error
root@ubuntu:/home/john# flash_lock -u /dev/mtd0
flash_lock: error!: could not unlock device: /dev/mtd0

             error 5 (Input/output error)

Now, no such issue. Thanks

Tested-by: John Garry <john.garry@huawei.com>

> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> ---
>   drivers/mtd/spi-nor/spi-nor.c | 22 ++++++++++++++++++++++
>   1 file changed, 22 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index caf0c109cca0..4376d8ad5834 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -819,6 +819,17 @@ static int spi_nor_sr_ready(struct spi_nor *nor)
>   			dev_err(nor->dev, "Programming Error occurred\n");
>   
>   		spi_nor_clear_sr(nor);
> +
> +		/*
> +		 * WEL bit remains set to one when an erase or page program
> +		 * error occurs. Issue a Write Disable command to protect
> +		 * against inadvertent writes that can possibly corrupt the
> +		 * contents of the memory.
> +		 */
> +		ret = spi_nor_write_disable(nor);
> +		if (ret)
> +			return ret;
> +
>   		return -EIO;
>   	}
>   
> @@ -875,6 +886,17 @@ static int spi_nor_fsr_ready(struct spi_nor *nor)
>   			"Attempted to modify a protected sector.\n");
>   
>   		spi_nor_clear_fsr(nor);
> +
> +		/*
> +		 * WEL bit remains set to one when an erase or page program
> +		 * error occurs. Issue a Write Disable command to protect
> +		 * against inadvertent writes that can possibly corrupt the
> +		 * contents of the memory.
> +		 */
> +		ret = spi_nor_write_disable(nor);
> +		if (ret)
> +			return ret;
> +
>   		return -EIO;
>   	}
>   
> 


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