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Subject: Re: [PATCH v2 1/1] mtd: spi-nor: micron-st: Enable locking for
 n25q256ax1/mt25qu256a
Message-ID: <a1411e79-d0ec-31e7-a190-ec2622928070@amazon.com>
Date:   Thu, 20 Oct 2022 12:15:41 +0300
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To:     Michael Walle <michael@walle.cc>
CC:     <tudor.ambarus@microchip.com>, <pratyush@kernel.org>,
        <miquel.raynal@bootlin.com>, <richard@nod.at>, <vigneshr@ti.com>,
        <linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <talel@amazon.com>, <jonnyc@amazon.com>, <hhhawa@amazon.com>,
        <hanochu@amazon.com>, <itamark@amazon.com>, <shellykz@amazon.com>,
        <amitlavi@amazon.com>, <dkl@amazon.com>,
        "Farber, Eliav" <farbere@amazon.com>
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From:   "Farber, Eliav" <farbere@amazon.com>
In-Reply-To: <41a05a89cd30b21dce866bc3209fe836@walle.cc>
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On 10/19/2022 1:23 PM, Michael Walle wrote:
> Am 2022-10-19 11:52, schrieb Farber, Eliav:
>> On 10/19/2022 12:38 PM, Michael Walle wrote:
>>> Am 2022-10-19 11:25, schrieb Farber, Eliav:
>>>> On 10/19/2022 11:21 AM, Michael Walle wrote:
>>>>> Hi,
>>>>>
>>>>> Am 2022-10-19 09:16, schrieb Eliav Farber:
>>>>>> n25q256ax1 [1] and mt25qu256a [2] (both have same jedec_id -
>>>>>> 0x20bb19)
>>>>>> use the 4 bit Block Protection scheme and support Top/Bottom
>>>>>> protection
>>>>>> via the BP and TB bits of the Status Register.
>>>>>> BP3 is located in bit 6 of the Status Register.
>>>>>> Tested on both n25q256ax1 and mt25qu256a.
>>>>>>
>>>>>> [1]
>>>>>> https://www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/n25q/n25q_256mb_3v.pdf 
>>>>>>
>>>>>> [2]
>>>>>> https://www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/mt25q/die-rev-a/mt25q_qljs_u_256_aba_0.pdf 
>>>>>>
>>>>>
>>>>> If you respin, you can use a "Link:" tag for the URL above.
>>>>
>>>> Ack.
>>>>
>>>>>> Signed-off-by: Eliav Farber <farbere@amazon.com>
>>>>>> ---
>>>>>> xxd -p
>>>>>> /sys/devices/platform/soc/fd882000.spi/spi_master/spi0/spi0.0/spi-nor/sfdp 
>>>>>>
>>>>>> 53464450060101ff00060110300000ff84000102800000ffffffffffffff
>>>>>> ffffffffffffffffffffffffffffffffffffe520fbffffffff0f29eb276b
>>>>>> 273b27bbffffffffffff27bbffff29eb0c2010d80f520000244a99008b8e
>>>>>> 03d4ac0127387a757a75fbbdd55c4a0f82ff81bd3d36ffffffffffffffff
>>>>>> ffffffffffffffffffe7ffff21dcffff
>>>>>>
>>>>>> md5sum
>>>>>> /sys/devices/platform/soc/fd882000.spi/spi_master/spi0/spi0.0/spi-nor/sfdp 
>>>>>>
>>>>>> 5ea738216f68c9f98987bb3725699a32
>>>>>> /sys/devices/platform/soc/fd882000.spi/spi_master/spi0/spi0.0/spi-nor/sfdp 
>>>>>>
>>>>>> cat
>>>>>> /sys/devices/platform/soc/fd882000.spi/spi_master/spi0/spi0.0/spi-nor/jedec_id 
>>>>>>
>>>>>> 20bb19104400
>>>>>>
>>>>>> cat
>>>>>> /sys/devices/platform/soc/fd882000.spi/spi_master/spi0/spi0.0/spi-nor/partname 
>>>>>>
>>>>>> mt25qu256a
>>>>>>
>>>>>> cat
>>>>>> /sys/devices/platform/soc/fd882000.spi/spi_master/spi0/spi0.0/spi-nor/manufacturer 
>>>>>>
>>>>>> st
>>>>>
>>>>> That's the mt25qu256a SFDP. What about the n25q256ax1?
>>>>
>>>> On the same card, with same NOR flash memory I'm running two
>>>> different
>>>> kernel versions.
>>>> First version is quite old - 4.19.239 which does not support
>>>> mt25qu256a
>>>> and therefore device is detected as n25q256ax1.
>>>> Second version is 6.1.0-rc1 and it detects the same device as
>>>> mt25qu256a.
>>>> So I was able to dump SFDP when running version 6.1.0-rc1, but not
>>>> when
>>>> running 4.19.239 which does not support the sysfs to dump the SFPD
>>>> information.
>>>> I checked that locking works with my changes when running on both
>>>> kernel
>>>> versions.
>>>
>>> So you've only tested on an mt25qu256a, correct? Then you should only
>>> add the locking to this flash device. (and maybe backport the
>>> mt25qu256a
>>> to your older kernel).
>>
>> I dumped SFDP tables only for mt25qu256a, but as I mentioned I tested
>> locking functionality for both (on 4.19.239 which detects the device as
>> n25q256ax1 and on 6.1.0-rc1  which detects the device as mt25qu256a).
>> This is the flow I used for testing the change on both versions:
>
> You said you've tested on the same board, thus it has the same flash
> device. But with the older kernel it was detected as a different part.
>
> So the question is, what is the correct part number? I.e. what is the
> _actual_ flash device soldered on your board?

I have found out that we use MT25QU256ABA8ESF-0SIT so I'll release a
patch for mt25qu256a only.

--
Thanks, Eliav