From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ew0-f49.google.com ([209.85.215.49]) by canuck.infradead.org with esmtps (Exim 4.72 #1 (Red Hat Linux)) id 1QDBhB-0007qM-J6 for linux-mtd@lists.infradead.org; Fri, 22 Apr 2011 08:26:34 +0000 Received: by ewy3 with SMTP id 3so144570ewy.36 for ; Fri, 22 Apr 2011 01:26:31 -0700 (PDT) Subject: Re: dangerous NAND_BBT_SCANBYTE1AND6 From: Artem Bityutskiy To: Ivan Djelic In-Reply-To: <20110421171046.GA790@parrot.com> References: <4DB052DB.7040308@parrot.com> <20110421171046.GA790@parrot.com> Content-Type: text/plain; charset="UTF-8" Date: Fri, 22 Apr 2011 11:23:36 +0300 Message-ID: <1303460616.2757.52.camel@localhost> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: "linux-mtd@lists.infradead.org" , Brian Norris , Matthieu CASTET Reply-To: dedekind1@gmail.com List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2011-04-21 at 19:10 +0200, Ivan Djelic wrote: > On Thu, Apr 21, 2011 at 04:52:59PM +0100, Matthieu Castet wrote: > > Hi, > > > > I believe NAND_BBT_SCANBYTE1AND6 behavior is very dangerous. > > We have a ST flash where ecc where but on bit 5 and 6. > > With new kernel all block are bad. > > > > Is this option is really needed ? > > ST datasheet say [1]. We already check the first Word. > > Why do we need to check the 6th Byte ? > > I agree with Matthieu, NAND_BBT_SCANBYTE1AND6 code also seems wrong to me. This just means that we need a better way for drivers to inform the generic code about how exactly blocks are marked as bad. Probably drivers could describe this with a data structure, and sometimes even provide a "is_block_bad()" function. The options seem to be not enough. -- Best Regards, Artem Bityutskiy (Артём Битюцкий)