linux-kernel - Re: [PATCH v2 3/4] dt-bindings: mtd: macronix,mx25l12833f: add SPI-NOR chip

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Date: Tue, 2 Jul 2024 06:00:48 +0100
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Erez <erezgeva2@...il.com>
Cc: Esben Haabendal <esben@...nix.com>, Erez Geva <erezgeva@...ime.org>,
 linux-mtd@...ts.infradead.org, Pratyush Yadav <pratyush@...nel.org>,
 Michael Walle <mwalle@...nel.org>, linux-kernel@...r.kernel.org,
 Miquel Raynal <miquel.raynal@...tlin.com>,
 Richard Weinberger <richard@....at>, Vignesh Raghavendra <vigneshr@...com>,
 devicetree@...r.kernel.org, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Subject: Re: [PATCH v2 3/4] dt-bindings: mtd: macronix,mx25l12833f: add
 SPI-NOR chip



On 7/1/24 6:08 PM, Erez wrote:
> On Mon, 1 Jul 2024 at 12:15, Tudor Ambarus <tudor.ambarus@...aro.org> wrote:
>>
>>
>>
>> On 7/1/24 10:46 AM, Erez wrote:
>>> When using mx25l12805d, we do not read SFDP.
>>> As it uses the no-SFDP flags.
>>> When using mx25l12833f hardware with mx25l12805d driver, it did not
>>> try to read the SFDP.
>>> Yet mx25l12833f does have SFDP, when I remove the no-SFDP flags, the
>>> driver fetch the SFDP.
>>>
>>> Secondly SFDP does not contain OTP information.
>>>
>>> mx25l12805d has two OTP regions of 128 KiB and 384 KiB (yes asymmetric).
>>> While mx25l12833f has two OTP regions of 512 KiB.
>>>
>>> How do we handle it?
>>
>> You would first try to parse SFDP and initialize the flash based on
>> SFDP. If there's no SFDP then you fallback to the flags declared at
>> flash declaration. Esben had a try recently, see [1]. I don't know if
>> there's any progress in that direction.
>>
>> Also, you haven't mentioned anything about the testing. Do you have the
>> flash?
>>
>> [1]
>> https://lore.kernel.org/linux-mtd/20240603-macronix-mx25l3205d-fixups-v2-0-ff98da26835c@geanix.com/
> 
> Looking at "mtd: spi-nor: macronix: workaround for device id re-use"
> I guess it can be applied to all Macronix devices.

No, no, we're going to do it individually just where it's needed.
Issuing unsupported commands is not that great.

> Adding something like the following in macronix_nor_default_init():
> 
> if (info>no_sfdp_flags)
>     info>no_sfdp_flags |= SPI_NOR_TRY_SFDP
> 
> It seems Macronix did many reuse of IDs.
> I saw it with "mx25l12833f" reusing "mx25l12805d".
> And Esben saw it with MX25L3233F reusing "MX25L3205D".
> 
> The only thing I notice is the flash using the same size.
> A sort of "backward" compatible.
> 
> Erez