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 1ZgT4R-0005qT-4t for linux-mtd@lists.infradead.org; Mon, 28 Sep 2015 07:42:00 +0000 Date: Mon, 28 Sep 2015 09:41:34 +0200 From: Boris Brezillon To: "Bean Huo =?UTF-8?B?6ZyN5paM5paM?= (beanhuo)" Cc: "dedekind1@gmail.com" , "adrian.hunter@intel.com" , "computersforpeace@gmail.com" , "baruch@tkos.co.il" , "asierra@xes-inc.com" , "guz.fnst@cn.fujitsu.com" , "gsi@denx.de" , "richard@nod.at" , David Woodhouse , "linux-mtd@lists.infradead.org" , "Frank Liu =?UTF-8?B?5YiY576k?= (frankliu)" , Andrea Scian , "Peter Pan =?UTF-8?B?5r2Y5p+P5a6P?= (peterpan)" , "Karl Zhang =?UTF-8?B?5byg5Y+M6ZSj?= (karlzhang)" , Iwo Mergler , "Jeff Lauruhn (jlauruhn)" , Stefan Roese , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 0/9] drivers:mtd:UBI: add bakvol module for MLC NAND paired page issue Message-ID: <20150928094134.2ab8557e@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: , Hi Bean, Next time you send a patch series, could send all the patches in reply to the cover letter? On Mon, 28 Sep 2015 07:02:35 +0000 Bean Huo =E9=9C=8D=E6=96=8C=E6=96=8C (beanhuo) wrote: > Hello, >=20 > This series aims at adding a bakvol module for MLC NAND paired page > Power loss protection. > MLC NAND paired page power loss is a known issue so far, MLC NAND pages a= re > coupled in a sense that if you cut power while writing to a page, you cor= rupt not only > this page, but also one of the previous pages which is paired with the cu= rrent one. > Currently, there is no a perfect solution for this.=20 > This paired page solution is based on NAND multiple plane program feature= . For this > Patch, only used dual plane page program, means two different plane pages= can > Be programmed together at the same time. > Dual plane page program only implements in backup operation. Only lower p= age data > Be duplicated and back up into a internal log volume by dual plane progra= m method. Hm, I'm not very fond of the idea, especially because of the complexity caused by dual plane program operations (you can't take a random block to write your backup on it, which means WL is complexified too), and the fact that you're duplicating data (thus introducing a performance penalty and storage overhead). >=20 > This patch has been testing on Micron 70s/80s/90s MLC NAND. > Of course there are some places needed to be improved and simplified. >=20 > Any suggestion and comments welcomed. Sure, I'll try to review it soon. Thanks for submitting those patches. Best Regards, Boris --=20 Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com