From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx.dave-tech.it ([2.229.21.40]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1adh7K-00015l-D9 for linux-mtd@lists.infradead.org; Wed, 09 Mar 2016 16:37:47 +0000 Subject: Re: [PATCH 1/2] mtd: nand: use a lower value for badblockbits when working with MLC NAND To: Boris Brezillon , =?UTF-8?B?QmVhbiBIdW8g6ZyN5paM5paMIChiZWFuaHVvKQ==?= References: <20160309152638.0b5e9250@bbrezillon> Cc: "linux-mtd@lists.infradead.org" , Brian Norris From: Andrea Scian Message-ID: <56E0513D.5000508@dave-tech.it> Date: Wed, 9 Mar 2016 17:37:17 +0100 MIME-Version: 1.0 In-Reply-To: <20160309152638.0b5e9250@bbrezillon> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Il 09/03/2016 15:26, Boris Brezillon ha scritto: > On Tue, 1 Mar 2016 14:47:21 +0000 > Bean Huo 霍斌斌 (beanhuo) wrote: > >> Hi, Andrea and Boris >> This is a historical subject, and talked before. >> From our field issues, 8 bits of bad block mark for MLC NAND is not reasonable. >> Because of bitflip on bad block mark, regard one good block as a bad block is common >> Issue. Especially first time boot after reflow. The solution is modified this value to 4 for MLC >> NAND by hand, and the factory BB mark is “0x00”. >> I think, 4 bits for MLC NAND make sense. > > > I'm tempted to say "let's start with this value and see what happens in > real world". If we want to be a bit more conservative we could decide > to chose 2, which should address most problems too (during my tests, I > never seen such a huge concentration of bitflips in the same byte). > > Brian, Andrea, what do you think? > I'm currently using 4 on my custom kernel. On all datasheet I've seen factory bad block marker is 0x00 and the same is (AFAIK) used by MTD to mark bad blocks. Kind Regards, -- Andrea SCIAN DAVE Embedded Systems