linux-kernel - Re: [PATCH] mtd: spi-nor: Fix w25q01jv flags

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Message-ID: <87bjkrzvk7.fsf@bootlin.com>
Date: Mon, 24 Nov 2025 09:25:28 +0100
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: "Michael Walle" <mwalle@...nel.org>
Cc: "Marc Olberding" <molberding@...dia.com>,  "Tudor Ambarus"
 <tudor.ambarus@...aro.org>,  "Pratyush Yadav" <pratyush@...nel.org>,
  "Richard Weinberger" <richard@....at>,  "Vignesh Raghavendra"
 <vigneshr@...com>,  <linux-mtd@...ts.infradead.org>,
  <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mtd: spi-nor: Fix w25q01jv flags

Hi,

On 24/11/2025 at 09:12:38 +01, "Michael Walle" <mwalle@...nel.org> wrote:

> Hi,
>
>>> +		.no_sfdp_flags = SECT_4K,
>>
>> This one is the right fix and should stand alone in its own patch (first
>> in the series if you add support for the block protection).
>
> Only if that flash really doesn't have SFDP. But since the entry
> didn't have a size property the flash *must* have SFDP in the first
> place.  Otherwise it won't even be probed. Please provide a dump of
> the SFDP tables, see [1].

SFDP data is in lore, but not the params which are missing (?) Marc, can
you compare with your data?
https://lore.kernel.org/all/20250110-winbond-6-12-rc1-nor-volatile-bit-v3-1-735363f8cc7d@bootlin.com/

> Also please provide the contents of
> /sys/kernel/debug/spi-nor/spiN.N/params.
>
> -michael

My understanding (which may clearly be erroneous) is that most of these
flashes support 4K blocks but somehow don't advertise it in their SFDP
data, so every time we describe a chip we must remember to tick that
flag. I guess all^Wmost chips have 4k blocks compatibility support, but in
general we prefer to use bigger blocks (the ones advertised in the SFDP
data). Michael, am I being mislead by the decades of history that went
through the spi-nor core? :)

> [1] https://docs.kernel.org/driver-api/mtd/spi-nor.html#minimum-testing-requirements
>
>>
>>>  		.fixups = &winbond_nor_multi_die_fixups,
>>>  	}, {
>>>  		.id = SNOR_ID(0xef, 0x50, 0x12),
>>
>> Thanks,
>> Miquèl