Re: [PATCH v4 5/5] mtd: spi-nor: micron-st: add comment for mt35xu02gcba

[Tudor Ambarus <tudor.ambarus@linaro.org>]

On 11/13/25 4:47 PM, Pratyush Yadav wrote:

Hi!

> On Wed, Nov 12 2025, Haibo Chen wrote:
> 
>> The MT35XU02GCBA flash device does not support chip erase,
>> according to its datasheet. It supports die erase, which
>> means the current driver implementation will likely need
>> to be converted to use die erase.
>>
>> Furthermore, similar to the MT35XU01GBBA, the
>> SPI_NOR_IO_MODE_EN_VOLATILE flag probably needs to be enabled.
>>
>> Link: https://datasheet.octopart.com/MT35XU02GCBA1G12-0AAT-Micron-datasheet-138896808.pdf
>> Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
>> Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
>> ---
>>  drivers/mtd/spi-nor/micron-st.c | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/mtd/spi-nor/micron-st.c b/drivers/mtd/spi-nor/micron-st.c
>> index c89c06b1fc61a581fea2e18732be2501a15715f9..f94e9d2d17bf4aa7c36ba3aa37d34f767a9f93ac 100644
>> --- a/drivers/mtd/spi-nor/micron-st.c
>> +++ b/drivers/mtd/spi-nor/micron-st.c
>> @@ -204,6 +204,16 @@ static const struct flash_info micron_nor_parts[] = {
>>  		.fixup_flags = SPI_NOR_IO_MODE_EN_VOLATILE,
>>  		.fixups = &mt35xu01gbba_fixups,
>>  	}, {
>> +		/*
>> +		 * The MT35XU02GCBA flash device does not support
>> +		 * chip erase, according to its datasheet.
>> +		 * It supports die erase, which means the current
>> +		 * driver implementation will likely need to be
>> +		 * converted to use die erase.
>> +		 * Furthermore, similar to the MT35XU01GBBA, the
>> +		 * SPI_NOR_IO_MODE_EN_VOLATILE flag probably needs
>> +		 * to be enabled.
>> +		 */
> 
> Maybe I am missing some context from previous patches, but why are we
> adding this comment here instead of fixing the support for this flash?
> What does "the driver will likely need to be converted to use die erase"
> mean? If it doesn't support chip erase, then it _does_ need to be fixed
> by using die erase.
> 
> Also, why does the flash "probably" need SPI_NOR_IO_MODE_EN_VOLATILE?
> Are you guessing based on datasheet and do not have the hardware at
> hand?

Yes, no hardware at hand. He can test with mt35xu01gbba which is a smaller
flash that share the datasheet with this flash, so that's why the TODO
and not a direct change.

> 
> The changelog should also explain _why_ this comment is added here, and
> not just repeat the text.
> 
>>  		.id = SNOR_ID(0x2c, 0x5b, 0x1c),
>>  		.name = "mt35xu02g",
>>  		.sector_size = SZ_128K,
>