From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from down.free-electrons.com ([37.187.137.238] helo=mail.free-electrons.com) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1adf4m-0000QZ-Pr for linux-mtd@lists.infradead.org; Wed, 09 Mar 2016 14:27:02 +0000 Date: Wed, 9 Mar 2016 15:26:38 +0100 From: Boris Brezillon To: "Bean Huo =?UTF-8?B?6ZyN5paM5paM?= (beanhuo)" Cc: "rnd4@dave-tech.it" , "andrea.scian@dave.eu" , "linux-mtd@lists.infradead.org" , "Brian Norris" Subject: Re: [PATCH 1/2] mtd: nand: use a lower value for badblockbits when working with MLC NAND Message-ID: <20160309152638.0b5e9250@bbrezillon> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 1 Mar 2016 14:47:21 +0000 Bean Huo =E9=9C=8D=E6=96=8C=E6=96=8C (beanhuo) wrote: > Hi, Andrea and Boris > This is a historical subject, and talked before.=20 > From our field issues, 8 bits of bad block mark for MLC NAND is not reaso= nable. > Because of bitflip on bad block mark, regard one good block as a bad bloc= k 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 =E2=80=9C0x00=E2=80=9D. > 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? --=20 Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com