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

[Jan Kiszka]

On 02.02.22 09:21, Michael Walle wrote:
> Am 2022-02-02 07:35, schrieb Jan Kiszka:
>> From: Jan Kiszka <jan.kiszka at 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 at 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.

I suppose this is why the original patch was placed way more down the
call chain... Back to square #1? Or can/should we split the request into
blocks?

Jan

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