linux-kernel - Re: [PATCH] mtd: core: handle flashes without OTP gracefully

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Message-ID: <499cf369-c98a-ac48-dfe6-6903314e9606@roeck-us.net>
Date:   Fri, 2 Jul 2021 06:49:55 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Michael Walle <michael@...le.cc>, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>
Subject: Re: [PATCH] mtd: core: handle flashes without OTP gracefully

On 7/2/21 2:38 AM, Michael Walle wrote:
> There are flash drivers which registers the OTP callbacks although the
> flash doesn't support OTP regions and return -ENODATA for these
> callbacks if there is no OTP. If this happens, the probe of the whole
> flash will fail. Fix it by handling the ENODATA return code and skip
> the OTP region nvmem setup.
> 
> Fixes: 4b361cfa8624 ("mtd: core: add OTP nvmem provider support")
> Reported-by: Guenter Roeck <linux@...ck-us.net>
> Signed-off-by: Michael Walle <michael@...le.cc>

Tested-by: Guenter Roeck <linux@...ck-us.net>

> ---
>   drivers/mtd/mtdcore.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
> index b5ccd3037788..6881d1423dd6 100644
> --- a/drivers/mtd/mtdcore.c
> +++ b/drivers/mtd/mtdcore.c
> @@ -880,7 +880,10 @@ static int mtd_otp_nvmem_add(struct mtd_info *mtd)
>   
>   	if (mtd->_get_user_prot_info && mtd->_read_user_prot_reg) {
>   		size = mtd_otp_size(mtd, true);
> -		if (size < 0)
> +		/* ENODATA means there is no OTP region */
> +		if (size == -ENODATA)
> +			size = 0;
> +		else if (size < 0)
>   			return size;
>   
>   		if (size > 0) {
> @@ -896,7 +899,10 @@ static int mtd_otp_nvmem_add(struct mtd_info *mtd)
>   
>   	if (mtd->_get_fact_prot_info && mtd->_read_fact_prot_reg) {
>   		size = mtd_otp_size(mtd, false);
> -		if (size < 0) {
> +		/* ENODATA means there is no OTP region */
> +		if (size == -ENODATA) {
> +			size = 0;
> +		} else if (size < 0) {
>   			err = size;
>   			goto err;
>   		}
>