linux-kernel - Re: [PATCH 1/2] nvmem: stm32: add warning when upper OTPs are updated

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Date:   Fri, 14 Oct 2022 17:44:04 +0200
From:   Patrick DELAUNAY <patrick.delaunay@...s.st.com>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>
Subject: Re: [PATCH 1/2] nvmem: stm32: add warning when upper OTPs are updated

Hi,

On 10/14/22 17:04, Patrick Delaunay wrote:
> As the upper OTPs are ECC protected, they support only one 32 bits word
> programming.
> For a second modification of this word, these ECC become invalid and
> this OTP will be no more accessible, the shadowed value is invalid.
>
> This patch adds a warning to indicate an upper OTP update, because this
> operation is dangerous as OTP is not locked by the driver after the first
> update to avoid a second update.
>
> Signed-off-by: Patrick Delaunay <patrick.delaunay@...s.st.com>
> ---
>
>   drivers/nvmem/stm32-romem.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/nvmem/stm32-romem.c b/drivers/nvmem/stm32-romem.c
> index 354be526897f..e3c3c333b5d1 100644
> --- a/drivers/nvmem/stm32-romem.c
> +++ b/drivers/nvmem/stm32-romem.c
> @@ -133,6 +133,9 @@ static int stm32_bsec_write(void *context, unsigned int offset, void *buf,
>   		}
>   	}
>   
> +	if (offset + bytes >= priv->lower * 4)


Here I miss a dependency for "priv->lower" with a other preliminary 
patch for STM32MP13x support.


> +		dev_warn(dev, "Update of upper OTPs with ECC protection (word programming, only once)\n");
> +
>   	return 0;
>   }
>   


Sorry,

I will sent a V2 soon


Patrick