[PATCH] mtd: spi-nor: core: Fix 16bit write sr_and_check status check

[Pratyush Yadav]

Hi Nathan,

On 24/03/22 07:00AM, Nathan Rossi wrote:
> From: Nathan Rossi <nathan.rossi at digi.com>
> 
> The spi_nor_write_16bit_sr_and_check function description describes that
> the function compares the value of the status and config registers after
> the write. However the function does not implement the status register
> compare only the config register check.
> 
> This causes the function to differ in behaviour to the equivalent
> spi_nor_write_sr1_and_check for non-16bit writes to the status register.
> This is important as other functions rely on the return code of
> spi_nor_write_sr_and_check. For example spi_nor_sr_unlock returns the
> result directly, which is returned to userspace such that failing to
> unlock the spi-nor device was resulting in a return code of 0 instead of
> the expected non-zero indicating the failure.
> 
> Signed-off-by: Nathan Rossi <nathan.rossi at digi.com>
> ---
>  drivers/mtd/spi-nor/core.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 04ea180118..d75d4f8a45 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1007,6 +1007,15 @@ static int spi_nor_write_16bit_sr_and_check(struct spi_nor *nor, u8 sr1)
>  	if (ret)
>  		return ret;
>  
> +	ret = spi_nor_read_sr(nor, sr_cr);
> +	if (ret)
> +		return ret;
> +
> +	if (sr1 != sr_cr[0]) {
> +		dev_dbg(nor->dev, "SR: read back test failed\n");
> +		return -EIO;
> +	}
> +
>  	if (nor->flags & SNOR_F_NO_READ_CR)
>  		return 0;

This patch seems exactly like [0]. I will pick that one if it applies on 
the current tree since it already has one Reviewed-by.

[0] https://lore.kernel.org/linux-mtd/20220126073227.3401275-1-chentsung@chromium.org/

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.