linux-kernel - Re: [EXT] Re: [Patch v3] drivers: mtd: spi-nor: Add flash property for mt25qu512a and mt35xu02g

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Message-ID: <a5049dca-e00e-ca28-7853-526ec7eac281@microchip.com>
Date:   Thu, 29 Aug 2019 08:09:17 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <ashish.kumar@....com>, <marek.vasut@...il.com>,
        <dwmw2@...radead.org>, <computersforpeace@...il.com>,
        <miquel.raynal@...tlin.com>, <richard@....at>, <vigneshr@...com>,
        <linux-mtd@...ts.infradead.org>
CC:     <kuldeep.singh@....com>, <linux-kernel@...r.kernel.org>
Subject: Re: [EXT] Re: [Patch v3] drivers: mtd: spi-nor: Add flash property
 for mt25qu512a and mt35xu02g



On 08/29/2019 10:47 AM, Ashish Kumar wrote:
> External E-Mail
> 
> 
> 
>> -----Original Message-----
>> From: linux-mtd <linux-mtd-bounces@...ts.infradead.org> On Behalf Of
>> Tudor.Ambarus@...rochip.com
>> Sent: Tuesday, August 27, 2019 5:34 PM
>> To: Ashish Kumar <ashish.kumar@....com>; marek.vasut@...il.com;
>> dwmw2@...radead.org; computersforpeace@...il.com;
>> miquel.raynal@...tlin.com; richard@....at; vigneshr@...com; linux-
>> mtd@...ts.infradead.org
>> Cc: Kuldeep Singh <kuldeep.singh@....com>; linux-kernel@...r.kernel.org
>> Subject: [EXT] Re: [Patch v3] drivers: mtd: spi-nor: Add flash property for
>> mt25qu512a and mt35xu02g
>>
>> Caution: EXT Email
>>
>> Hi, Ashish,
>>
>> On 08/13/2019 01:38 PM, Ashish Kumar wrote:
>>> External E-Mail
>>>
>>>
>>> mt25qu512a is rebranded after its spinoff from STM, so it is different
>>> only in term of operating frequency, initial JEDEC id is same as that
>>> of n25q512a. In order to avoid any confussion with respect to name new
>>> entry is added.
>>> This flash is tested for Single I/O and QUAD I/O mode on LS1046FRWY.
>>>
>>> mt35xu02g is Octal flash supporting Single I/O and QCTAL I/O and it
>>> has been tested on LS1028ARDB
>>>
>>> Signed-off-by: Kuldeep Singh <kuldeep.singh@....com>
>>> Signed-off-by: Ashish Kumar <ashish.kumar@....com>
>>> ---

cut

>>> +
>>> +     /* Micron */
>>> +     { "mt25qu512a", INFO6(0x20bb20, 0x104400, 64 * 1024, 1024, SECT_4K |
>>> +                             USE_FSR | SPI_NOR_DUAL_READ |
>>> +                             SPI_NOR_QUAD_READ | SPI_NOR_4B_OPCODES)
>>> + },
>>
>> I'm looking at the following datasheets: mt25qu512a [1] and n25q512a [2].
>> Both flashes have the same Extended Device ID data. What will happen, is
>> that you'll always hit the first valid entry, so "mt25qu512a", and you'll indicate
>> a 'wrong' flash name for n25q512a. If there is nothing that differentiate
>> between the two, maybe you can add a comment in the code that says that
>> "n25q512a" was re-branded to "mt25qu512a" after the STM spin-off.
>> Whatever solution will be, it will be better if you do it in a separate patch.
> Hi Tudor,
> Considering both are same, should I rename to mt25qu51a, and add SPI_NOR_4B_OPCODES or
> Keep n25q512a, and comment about mt25qu51a  and add SPI_NOR_4B_OPCODES.

I see two options:
1/ either rename "n25q512a" to "mt25qu512a (n25q512a)" and add the
SPI_NOR_4B_OPCODES
2/ or keep "n25q512a", add SPI_NOR_4B_OPCODES, and add a comment about
re-branding to mt25qu512a.

Which one do you like better? What about you, Vignesh?

> 
> For separate patch comment you mean split mt25qu512a and mt35xu02g into 2 patch.

yes, send a separate patch for mt35xu02g, as the changes are not related.
> 
>>

cut

>>> +     { "mt35xu02g",  INFO(0x2c5b1c, 0, 128 * 1024, 2048,
>>> +                     SECT_4K | USE_FSR | SPI_NOR_OCTAL_READ |
>>> +                     SPI_NOR_4B_OPCODES) },
>>
>> Is there a public datasheet for this flash?
> No,  data sheet in under NDA, I have asked micron FAE for public data sheet, will resend after the same is published. 
> 

No need to wait, I'll trust you. It was better if I could verify the info, but
if we can't, that's it. Just send a different patch for this change.

Cheers,
ta