Re: [PATCH v4] sf: Query write-protection status before operating the flash

[Michael Walle <michael@walle.cc>]

Am 2022-02-02 07:35, schrieb Jan Kiszka:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> Do not suggest successful operation if a flash area to be changed is
> actually locked, thus will not execute the request. Rather report an
> error and bail out. That's way more user-friendly than asking them to
> manually check for this case.
> 
> Derived from original patch by Chao Zeng.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> 
> This is the successor of "[PATCH V3] sf: Querying write-protect status
> before operating the flash", moving the test into the CLI API, see
> https://lore.kernel.org/u-boot/20220117175628.GQ2631111@bill-the-cat/.
> 
>  cmd/sf.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/cmd/sf.c b/cmd/sf.c
> index 8bdebd9fd8f..a24e04c690b 100644
> --- a/cmd/sf.c
> +++ b/cmd/sf.c
> @@ -287,6 +287,12 @@ static int do_spi_flash_read_write(int argc, char
> *const argv[])
>  		return 1;
>  	}
> 
> +	if (strncmp(argv[0], "read", 4) != 0 && flash->flash_is_locked &&
> +	    flash->flash_is_locked(flash, offset, len)) {
> +		printf("ERROR: flash area is locked\n");
> +		return 1;
> +	}

Much better to handle it here. But I'm not sure if this is doing
the right thing:

Eventually, this function is called:

/*
  * Return 1 if the entire region is locked (if @locked is true) or 
unlocked (if
  * @locked is false); 0 otherwise
  */
static int stm_check_lock_status_sr(struct spi_nor *nor, loff_t ofs, u64 
len,
                                     u8 sr, bool locked)

So I'd guess if you try to write to an area of the flash where only 
parts
are locked, you still see it as unlocked and thus there will be no 
error.
Which IMHO is even more confusing for a user.

-michael