From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtprelay04.ispgateway.de ([80.67.18.16]) by canuck.infradead.org with esmtp (Exim 4.52 #1 (Red Hat Linux)) id 1ECv0H-0005n4-MR for linux-mtd@lists.infradead.org; Wed, 07 Sep 2005 04:10:01 -0400 Received: from unknown (HELO deepspace9.in2soft.meep) (547986@[84.153.66.112]) (envelope-sender ) by smtprelay04.ispgateway.de (qmail-ldap-1.03) with SMTP for ; 7 Sep 2005 08:09:55 -0000 Message-ID: <431EA052.5010303@gmail.com> Date: Wed, 07 Sep 2005 10:09:54 +0200 From: Bernhard Priewasser MIME-Version: 1.0 To: kyungmin.park@samsung.com References: <0IM4002SYUMFJ8@mmp2.samsung.com> In-Reply-To: <0IM4002SYUMFJ8@mmp2.samsung.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-mtd@lists.infradead.org Subject: Re: [PATCH] OneNAND: Simple Bad Block handling support List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi all, Kyungmin, I'm still not completely clear about your bad block handling, sorry for bothering you another time. In onenand_scan() you call scan_bbt() which calls onenand_memory_bbt() which calls create_bbt() which builds the BBT using OOB data. Fine so far. But: the only time onenand_block_checkbad() is called is in onenand_erase() before issueing the (erase-)command to prevent erasing already scanned bad blocks. Question: what about reading and writing (onenand_write_ecc(), onenand_read_ecc())? There is no onenand_block_checkbad() before issueing the write/read command. Shouldn't this be done?? scan_bbt() is only called on initial scan, e.g. device boot. What if this happens very rarely and bad blocks due to wear occur; that meant you cannot provide data integrity. I wonder why this is not done in nand_base.c too. I'm afraid I missed some BBT stuff to gather in my investigations :-)... So please kindly excuse me if I'm wrong with my very limited MTD/OneNAND experience! Best Regards, Bernhard