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

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Message-ID: <CAOMqctTwrN3onS0EuW1ZB0ZDcw4X+WrKwnFbYizPpwXY8cCLWQ@mail.gmail.com>
Date:	Mon, 4 May 2015 15:39:44 +0200
From:	Michal Suchanek <hramrach@...il.com>
To:	Marek Vasut <marex@...x.de>
Cc:	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>,
	"Rafa?? Mi??ecki" <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 Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] MTD: spi-nor: add flag to not use sector erase.

On 4 May 2015 at 15:35, Marek Vasut <marex@...x.de> wrote:
> On Monday, May 04, 2015 at 03:18:56 PM, Michal Suchanek wrote:
>> On 4 May 2015 at 14:12, Marek Vasut <marex@...x.de> wrote:
>> > On Monday, May 04, 2015 at 01:11:03 PM, Michal Suchanek wrote:
>> >>
>> >> It mentions both
>> >> 32KB Block Erase (BE) (52H)
>> >> and
>> >> 64KB Block Erase (BE) (D8H)
>> >
>> > The SPI NOR framework will use 0xbe opcode, no problem.
>> >
>> >> So the chip probably tries its best to be compatible with any command
>> >> set and this last patch is not needed. The memory organization table
>> >> on page 7 is not all that reassuring, though.
>> >
>> > Which exact part do you refer to please ?
>>
>> Start of page 7 where it says sector size 32/64K in either datasheet.
>>
>> It can refer to both BE opcode variants being supported but it's quite
>> unclear.
>
> My guess here would be that the internal organisation of the SPI NOR is
> in 4k blocks, which is no surprise really. My understanding is that opcode
> 0x52 erases 8x4k sector (ie. 32k of data) while 0xd8 erases 16x4k sector
> (ie. 64k of data). I don't see any problem here -- there are two different
> opcodes which do two different things and their behavior matches the one on
> various other SPI NORs.
>
>> Write protection seems to be calculated in 4k sectors and not blocks
>> so the block size does not seem very relevant.
>
> See above. Does it make sense now please ?
>

Yes,

makes sense.

Thanks

Michal
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