From: Marek Vasut <marex@denx.de>
To: Michal Suchanek <hramrach@gmail.com>
Subject: Re: [PATCH 3/3] MTD: spi-nor: add flag to not use sector erase.
Date: Fri, 1 May 2015 01:13:50 +0200
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Cc: David Woodhouse <dwmw2@infradead.org>,
        Brian Norris <computersforpeace@gmail.com>, zajec5@gmail.com,
        Alison Chaiken <alison_chaiken@mentor.com>,
        Ben Hutchings <ben@decadent.org.uk>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        "Bean Huo \(beanhuo\)" <beanhuo@micron.com>,
        "grmoore@altera.com" <grmoore@altera.com>,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
References: <cover.1430430153.git.hramrach@gmail.com> <35add8df33b17e2354d9496eba8597d9d8488f30.1430430153.git.hramrach@gmail.com>
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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@gmail.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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