From: Michael Walle <michael@walle.cc>
To: Tudor.Ambarus@microchip.com
Cc: vigneshr@ti.com, richard@nod.at, linux-kernel@vger.kernel.org,
linux-mtd@lists.infradead.org, miquel.raynal@bootlin.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH 1/2] mtd: spi-nor: atmel: remove global SNOR_F_HAS_LOCK
Date: Thu, 01 Oct 2020 16:12:43 +0200 [thread overview]
Message-ID: <871da0d058ba89320615098ee26150b3@walle.cc> (raw)
In-Reply-To: <5eb8f95c-e9d5-6043-fb7d-bffcda044262@microchip.com>
Am 2020-10-01 16:06, schrieb Tudor.Ambarus@microchip.com:
> On 10/1/20 3:28 PM, Michael Walle wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know
>> the content is safe
>>
>> This is considered bad for the following reasons:
>> (1) We only support the block protection with BPn bits for write
>> protection. Not all Atmel parts support this.
>> (2) Newly added flash chip will automatically inherit the "has
>> locking" support and thus needs to explicitly tested. Better
>> be opt-in instead of opt-out.
>> (3) There are already supported flashes which don't support the
>> locking
>> scheme. So I assume this wasn't properly tested before adding
>> that
>> chip; which enforces my previous argument that locking
>> support should
>> be an opt-in.
>>
>> Remove the global flag and add individual flags to all flashes
>> which supports BP locking. In particular the following flashes
>> don't support the BP scheme:
>> - AT26F004
>> - AT25SL321
>> - AT45DB081D
>>
>> Signed-off-by: Michael Walle <michael@walle.cc>
>> ---
>> drivers/mtd/spi-nor/atmel.c | 28 +++++++++-------------------
>> 1 file changed, 9 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/mtd/spi-nor/atmel.c b/drivers/mtd/spi-nor/atmel.c
>> index 3f5f21a473a6..49d392c6c8bc 100644
>> --- a/drivers/mtd/spi-nor/atmel.c
>> +++ b/drivers/mtd/spi-nor/atmel.c
>> @@ -10,37 +10,27 @@
>>
>> static const struct flash_info atmel_parts[] = {
>> /* Atmel -- some are (confusingly) marketed as "DataFlash" */
>> - { "at25fs010", INFO(0x1f6601, 0, 32 * 1024, 4, SECT_4K) },
>> - { "at25fs040", INFO(0x1f6604, 0, 64 * 1024, 8, SECT_4K) },
>> + { "at25fs010", INFO(0x1f6601, 0, 32 * 1024, 4, SECT_4K |
>> SPI_NOR_HAS_LOCK) },
>> + { "at25fs040", INFO(0x1f6604, 0, 64 * 1024, 8, SECT_4K |
>> SPI_NOR_HAS_LOCK) },
>
> after a quick look in the datasheets of these flashes, I suspect that
> what we have now in the SPI NOR core for SR locking does not work for
> them. They probably supported just "unlock all", clearing all the
> BP bits. Anyway, different problem.
>>
>> - { "at25df041a", INFO(0x1f4401, 0, 64 * 1024, 8, SECT_4K) },
>> - { "at25df321", INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K) },
>> - { "at25df321a", INFO(0x1f4701, 0, 64 * 1024, 64, SECT_4K) },
>> - { "at25df641", INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K) },
>> + { "at25df041a", INFO(0x1f4401, 0, 64 * 1024, 8, SECT_4K |
>> SPI_NOR_HAS_LOCK) },
>
> this one does not support BP locking:
> https://www.adestotech.com/wp-content/uploads/doc3668.pdf
>
>> + { "at25df321", INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K |
>> SPI_NOR_HAS_LOCK) },
>
> neither this one:
> https://datasheet.octopart.com/AT25DF321-S3U-Atmel-datasheet-8700896.pdf
>
>> + { "at25df321a", INFO(0x1f4701, 0, 64 * 1024, 64, SECT_4K |
>> SPI_NOR_HAS_LOCK) },
>
> nor this one: https://www.adestotech.com/wp-content/uploads/doc3686.pdf
>
>> + { "at25df641", INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K |
>> SPI_NOR_HAS_LOCK) },
>
> nor this one: https://www.adestotech.com/wp-content/uploads/doc3680.pdf
>
> I stop here.
These are all the ones which use the global unlock. I cannot just skip
the HAS_LOCK bit here, because otherwise this patch wouldn't be
backwards
compatibe. Yes I missed that in the commit log, my bad.
-michael
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next prev parent reply other threads:[~2020-10-01 14:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 12:28 [RFC PATCH 1/2] mtd: spi-nor: atmel: remove global SNOR_F_HAS_LOCK Michael Walle
2020-10-01 12:28 ` [RFC PATCH 2/2] mtd: spi-nor: sst: " Michael Walle
2020-10-01 13:21 ` [RFC PATCH 1/2] mtd: spi-nor: atmel: " Tudor.Ambarus
2020-10-01 14:06 ` Tudor.Ambarus
2020-10-01 14:12 ` Michael Walle [this message]
2020-10-01 14:25 ` Tudor.Ambarus
2020-10-01 14:37 ` Michael Walle
2020-10-01 15:25 ` Tudor.Ambarus
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