linux-kernel - Re: [PATCH 3/3] MTD: spi-nor: add flag to not use sector erase.

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Date:	Fri, 1 May 2015 01:13:50 +0200
From:	Marek Vasut <marex@...x.de>
To:	Michal Suchanek <hramrach@...il.com>
Cc:	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>, zajec5@...il.com,
	Alison Chaiken <alison_chaiken@...tor.com>,
	Ben Hutchings <ben@...adent.org.uk>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	"Bean Huo \(beanhuo\)" <beanhuo@...ron.com>,
	"grmoore@...era.com" <grmoore@...era.com>,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] MTD: spi-nor: add flag to not use sector erase.

On Thursday, April 30, 2015 at 11:13:12 PM, Michal Suchanek wrote:
> The sector size of the flash memory is unclear from datasheet or may
> possibly vary between chips so add a flag to always use 4k blocks.
> 
> Currently 4k blocks are always used when possible but in the future
> somebody might want to do some optimizations with sector erase.
> 
> Signed-off-by: Michal Suchanek <hramrach@...il.com>

I _think_ you might be able to determine the size, no ?

One way is to ask the vendor, but you can also try something like:
1) erase the whole SPI NOR
2) overwrite it with zeroes (or ones ? I think it should be all ones after 
erasing).
3) Erase sector 0
4) Read some 128 KiB back
5) Observe what is the difference.

Best regards,
Marek Vasut
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