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

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Date:	Mon, 4 May 2015 16:11:26 +0200
From:	Marek Vasut <marex@...x.de>
To:	Michal Suchanek <hramrach@...il.com>
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 Monday, May 04, 2015 at 03:39:44 PM, Michal Suchanek wrote:
> 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.

I'm glad to hear this got cleared up, thanks ! :)

Best regards,
Marek Vasut
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