From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pop.scorch.co.nz ([203.167.215.14] helo=firstline.co.nz) by canuck.infradead.org with smtp (Exim 4.62 #1 (Red Hat Linux)) id 1FnBAy-0003HR-7i for linux-mtd@lists.infradead.org; Mon, 05 Jun 2006 05:15:16 -0400 From: Charles Manning To: linux-mtd@lists.infradead.org, tglx@linutronix.de Subject: Re: NAND OOB Questions... Date: Mon, 5 Jun 2006 21:23:47 +1200 References: <32905508.1149179928067.JavaMail.root@elwamui-karabash.atl.sa.earthlink.net> <1149495264.11983.12.camel@localhost.localdomain> In-Reply-To: <1149495264.11983.12.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200606052123.47126.manningc2@actrix.gen.nz> Cc: Steve Finney List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Monday 05 June 2006 20:14, Thomas Gleixner wrote: > On Thu, 2006-06-01 at 09:38 -0700, Steve Finney wrote: > > 1) The Samsung K9F56* NAND chip allows doing more than one write > > to the OOB area of a page without an erase; the second write > > may zero bits that were set to 1 by the first write. Is the Samsung > > Bits can not be set to 1 by the first write. FLASH cells are set to 1 by > erasing and programming can set bits to 0. > > > chip unusual in this, or is this normal NAND behavior? (I believe > > this would be normal for NOR flash). > > On NOR you can do this almost unlimited. NAND is much more restricted > vs. write ordering. Just one point of clarification that tglx might not have spelled out clearly here. In both NAND and NOR you cannot set a 0 bit back to a 1 bit by programming. You can only do this by erasing the erasable block. Where NOR and NAND differ is that if you program a pattern into NOR that tries to set a 0 to a 1 then (in most cases) the programming operation will be aborted. However, NAND will program the zeros only and 1 bits are just "don't care".