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

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Message-ID: <mafs0wm3s8x4f.fsf@kernel.org>
Date: Fri, 14 Nov 2025 16:14:24 +0100
From: Pratyush Yadav <pratyush@...nel.org>
To: Tudor Ambarus <tudor.ambarus@...aro.org>
Cc: Pratyush Yadav <pratyush@...nel.org>,  Haibo Chen <haibo.chen@....com>,
  Michael Walle <mwalle@...nel.org>,  Miquel Raynal
 <miquel.raynal@...tlin.com>,  Richard Weinberger <richard@....at>,
  Vignesh Raghavendra <vigneshr@...com>,  linux-mtd@...ts.infradead.org,
  linux-kernel@...r.kernel.org,  imx@...ts.linux.dev
Subject: Re: [PATCH v4 5/5] mtd: spi-nor: micron-st: add comment for
 mt35xu02gcba

On Thu, Nov 13 2025, Tudor Ambarus wrote:

> 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@...aro.org>
>>> Signed-off-by: Haibo Chen <haibo.chen@....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.

Okay, fair enough. I think the wording of the comment and commit message
are kind of vague though. So I will do some massaging when applying.

[...]

-- 
Regards,
Pratyush Yadav