From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from DB3EHSOBE006.bigfish.com (db3ehsobe006.messaging.microsoft.com [213.199.154.144]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "Microsoft Secure Server Authority" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 4E06EB7039 for ; Tue, 20 Dec 2011 05:38:31 +1100 (EST) Message-ID: <4EEF849B.7030804@freescale.com> Date: Mon, 19 Dec 2011 12:38:19 -0600 From: Scott Wood MIME-Version: 1.0 To: Subject: Re: [PATCH 3/3] mtd/nand : workaround for Freescale FCM to support large-page Nand chip References: <1322973098-2528-1-git-send-email-shuo.liu@freescale.com> <1322973098-2528-3-git-send-email-shuo.liu@freescale.com> <4EDEAEB9.6020703@freescale.com> <1323724195.2297.11.camel@koala> <4EE66EFE.1050608@freescale.com> <1323724784.2297.20.camel@koala> <4EE6725C.3050706@freescale.com> <1324132520.4240.26.camel@sauron.fi.intel.com> In-Reply-To: <1324132520.4240.26.camel@sauron.fi.intel.com> Content-Type: text/plain; charset="UTF-8" Cc: Artem.Bityutskiy@nokia.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, shuo.liu@freescale.com, linux-mtd@lists.infradead.org, akpm@linux-foundation.org, dwmw2@infradead.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 12/17/2011 08:35 AM, Artem Bityutskiy wrote: > On Mon, 2011-12-12 at 15:30 -0600, Scott Wood wrote: >> On 12/12/2011 03:19 PM, Artem Bityutskiy wrote: >>> On Mon, 2011-12-12 at 15:15 -0600, Scott Wood wrote: >>>> NAND chips come from the factory with bad blocks marked at a certain >>>> offset into each page. This offset is normally in the OOB area, but >>>> since we change the layout from "4k data, 128 byte oob" to "2k data, 64 >>>> byte oob, 2k data, 64 byte oob" the marker is no longer in the oob. On >>>> first use we need to migrate the markers so that they are still in the oob. >>> >>> Ah, I see, thanks. Are you planning to implement in-kernel migration or >>> use a user-space tool? >> >> That's the kind of answer I was hoping to get from Shuo. :-) >> >> Most likely is a firmware-based tool, but I'd like there to be some way >> for the tool to mark that this has happened, so that the Linux driver >> can refuse to do non-raw accesses to a chip that isn't marked as having >> been migrated (or at least yell loudly in the log). >> >> Speaking of raw accesses, these are currently broken in the eLBC >> driver... we need some way for the generic layer to tell us what kind of >> access it is before the transaction starts, not once it wants to read >> out the buffer (unless we add more hacks to delay the start of a read >> transaction until first buffer access...). We'd be better off with a >> high-level "read page/write page" function that does the whole thing >> (not just buffer access, but command issuance as well). > > It looks like currently you can re-define chip->read_page, so I guess > you should rework MTD and make chip->write_page re-definable? Unless something has changed very recently, there is no chip->read_page or chip->write_page. There is chip->ecc.read_page and chip->ecc.write_page, but they are too low-level. What we'd need to replace is a portion of nand_do_read_ops()/nand_do_write_ops(). -Scott