From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fed1rmmtao105.cox.net ([68.230.241.41]) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1M6w45-0004tA-Gx for linux-mtd@lists.infradead.org; Thu, 21 May 2009 00:23:39 +0000 Message-ID: <4A149EF2.1010208@boundarydevices.com> Date: Wed, 20 May 2009 17:23:14 -0700 From: Troy Kisky MIME-Version: 1.0 To: "Narnakaje, Snehaprabha" Subject: Re: [PATCH 2.6.30-rc6 3/3] NAND: Add 4-bit ECC support for large page NAND chips References: <1242682705-19845-1-git-send-email-nsnehaprabha@ti.com> <4A11F5FC.40709@boundarydevices.com> <4A11FA90.3060403@boundarydevices.com> <7A436F7769CA33409C6B44B358BFFF0C01138180E0@dlee02.ent.ti.com> <4A1454B8.3010605@boundarydevices.com> <7A436F7769CA33409C6B44B358BFFF0C01138184F0@dlee02.ent.ti.com> <4A1465AE.7090706@boundarydevices.com> <7A436F7769CA33409C6B44B358BFFF0C0113818603@dlee02.ent.ti.com> In-Reply-To: <7A436F7769CA33409C6B44B358BFFF0C0113818603@dlee02.ent.ti.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "davinci-linux-open-source@linux.davincidsp.com" , David Brownell , "linux-mtd@lists.infradead.org" , "tglx@linutronix.de" , "dwmw2@infradead.org" , "akpm@linux-foundation.org" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > > I explored nand_bbt, jffs2 using the OOB area. > > This is what I found - > 2 bytes at offset 0: BB markers > 4 bytes at offset 8: BBT magic number/data > 1 byte at offset 12: BBT version > 8 bytes at offset 16: JFFS2 clear markers > > So, it is better to start with offset 24 (there are few bytes in between, but it is better to leave them as-is). > > Dave, > > Did you have any comments? > > Thanks > Sneha If you have to move the ECC anyway, there really isn't a further compatibility problem with moving the JFFS2 bytes as well. 0-1 : BB marker 2-23 : Free space (JFFS2 will use) 24-63 : 4 x 10 bytes of ecc. This way, if the default ecc layout patch that I submitted is ever accepted, the code in this patch can be removed. Troy