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From: Alexander Sverdlin <alexander.sverdlin@nokia.com>
To: Pratyush Yadav <p.yadav@ti.com>
Cc: Michael Walle <michael@walle.cc>,
	linux-mtd@lists.infradead.org,
	Tudor Ambarus <tudor.ambarus@microchip.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mtd: spi-nor: mt25qu: Ignore 6th ID byte
Date: Thu, 25 Nov 2021 08:26:59 +0100	[thread overview]
Message-ID: <8742b6e8-c26e-47d7-0b77-67137d3de10f@nokia.com> (raw)
In-Reply-To: <20211123174206.bzh5yq2f7sgkqpmi@ti.com>

Hi Pratyush,

thanks for the quick reply!

On 23/11/2021 18:42, Pratyush Yadav wrote:
>> In my opinion, as I look into Micron or Macronix datasheets, write_proto has little to
>> do with erase_proto. (there is currently no separate erase_proto)
> I think this just worked for most flashes since both writes and erases 
> generally use 1-bit mode. 4 or 8 bit modes are generally used for reads 
> only.
> 
>> Before I come up with a totally wrong patch, wanted to ask your opinion, how should
>> it be solved, what do you think?
>>
>> I do not see any erase-related tables for this in JESD216C.
>> I also cannot come up with an example of a chip with erase != 1-1-0.
> See Micron MT35XU512ABA or Cypress S28HS512T (in spansion.c). Both have 
> erase in 8D-8D-8D mode.
> 
>> Shall I hardcode 1-1-0 for erase?
>> Shall I introduce erase_proto? What would be the logic for its setting/discovery?
> I think introducing erase_proto would be the sensible thing. You would 
> have to see if we can discover erase protocol from SFDP. But my question 
> is: is that really worth it? Do you really need that little bit speed 
> boost you'd get by transmitting write data in 4 bit mode, since the 
> large portion of the time would be spent in the chip actually flashing 
> the data.

The problem I have is not speed, but totally not working erase. And I don't want
to downgrade write functionality for other chips.

-- 
Best regards,
Alexander Sverdlin.

  reply	other threads:[~2021-11-25  7:29 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-19  8:04 Alexander A Sverdlin
2021-11-19 21:19 ` Michael Walle
2021-11-22  7:06   ` Alexander Sverdlin
2021-11-22 15:05     ` Michael Walle
2021-11-23  7:45       ` Alexander Sverdlin
2021-11-23  8:14         ` Michael Walle
2021-11-23 12:40           ` Alexander Sverdlin
2021-11-23 14:01             ` Michael Walle
2021-11-23 16:14               ` Tudor.Ambarus
2021-11-23 12:13       ` Alexander Sverdlin
2021-11-23 17:42         ` Pratyush Yadav
2021-11-25  7:26           ` Alexander Sverdlin [this message]
2021-11-30  9:49             ` Pratyush Yadav
2022-07-18 15:03 ` Tudor.Ambarus

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