Re: [PATCH v2 3/8] mtd: spi-nor: core: Use auto-detection only once

[<Tudor.Ambarus@microchip.com>]

On 3/21/22 14:14, Pratyush Yadav wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On 28/02/22 01:17PM, Tudor Ambarus wrote:
>> In case spi_nor_match_name() returned NULL, the auto detection was
>> issued twice. There's no reason to try to detect the same chip twice,
>> do the auto detection only once.
>>
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
>> ---
>>  drivers/mtd/spi-nor/core.c | 10 ++++++----
>>  1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
>> index f87cb7d3daab..b1d6fa65417d 100644
>> --- a/drivers/mtd/spi-nor/core.c
>> +++ b/drivers/mtd/spi-nor/core.c
>> @@ -2894,13 +2894,15 @@ static const struct flash_info *spi_nor_match_name(struct spi_nor *nor,
>>  static const struct flash_info *spi_nor_get_flash_info(struct spi_nor *nor,
>>                                                      const char *name)
>>  {
>> -     const struct flash_info *info = NULL;
>> +     const struct flash_info *info = NULL, *detected_info = NULL;
>>
>>       if (name)
>>               info = spi_nor_match_name(nor, name);
>>       /* Try to auto-detect if chip name wasn't specified or not found */
>> -     if (!info)
>> -             info = spi_nor_read_id(nor);
>> +     if (!info) {
>> +             detected_info = spi_nor_read_id(nor);
>> +             info = detected_info;
>> +     }
>>       if (IS_ERR_OR_NULL(info))
>>               return ERR_PTR(-ENOENT);
>>
>> @@ -2908,7 +2910,7 @@ static const struct flash_info *spi_nor_get_flash_info(struct spi_nor *nor,
>>        * If caller has specified name of flash model that can normally be
>>        * detected using JEDEC, let's verify it.
>>        */
>> -     if (name && info->id_len) {
>> +     if (name && !detected_info && info->id_len) {
>>               const struct flash_info *jinfo;
>>
>>               jinfo = spi_nor_read_id(nor);
> 
> I think the flow can be a little bit better. How about:
> 
>         if (name)
>                 info = spi_nor_match_name();
> 
>         if (!info) {
>                 info = spi_nor_read_id();
>                 if (IS_ERR_OR_NULL(info))
>                         return ERR_PTR(-ENOENT);
> 
>                 return info;
>         }

Here we miss the IS_ERR check in case info is retrieved with spi_nor_match_name().
Do you expect spi_nor_match_name() to ever return an error? As it is now it doesn't.
I'm fine either way. In case you want me to follow your suggestion, give me a sign
and I'll make a dedicated patch to move the IS_ERR_OR_NULL check. Will add your
Suggested-by tag.

Cheers,
ta
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