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

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Date:   Thu, 29 Aug 2019 14:46:48 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     <Tudor.Ambarus@...rochip.com>, <ashish.kumar@....com>,
        <marek.vasut@...il.com>, <dwmw2@...radead.org>,
        <computersforpeace@...il.com>, <miquel.raynal@...tlin.com>,
        <richard@....at>, <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

Hi,

On 29/08/19 1:39 PM, Tudor.Ambarus@...rochip.com wrote:
[...]
> 
>>>> +
>>>> +     /* 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

I would go with first option so as not to alarm the users who are used
to seeing n25q512a in kernel log. This option shows both old and new
brand names.

Regards
Vignesh

> 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
> 

-- 
Regards
Vignesh