From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout4.samsung.com ([203.254.224.34]) by bombadil.infradead.org with esmtp (Exim 4.72 #1 (Red Hat Linux)) id 1ONwSe-0007xe-6i for linux-mtd@lists.infradead.org; Sun, 13 Jun 2010 23:19:29 +0000 Received: from epmmp1 (mailout4.samsung.com [203.254.224.34]) by mailout4.samsung.com (Sun Java(tm) System Messaging Server 7u3-15.01 64bit (built Feb 12 2010)) with ESMTP id <0L3Z00MTH7GAAX20@mailout4.samsung.com> for linux-mtd@lists.infradead.org; Mon, 14 Jun 2010 08:19:22 +0900 (KST) Received: from TNRNDGASPAPP1.tn.corp.samsungelectronics.net ([165.213.149.150]) by mmp1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTPA id <0L3Z0098A7GAMF@mmp1.samsung.com> for linux-mtd@lists.infradead.org; Mon, 14 Jun 2010 08:19:22 +0900 (KST) Date: Mon, 14 Jun 2010 08:19:22 +0900 From: Kyungmin Park Subject: RE: [PATCH 1/2] mtd: OneNAND: Add runtime badblock check feature In-reply-to: <1276421200.19028.192.camel@localhost> To: dedekind1@gmail.com, 'Joonyoung Shim' Message-id: <012f01cb0b4e$db1a7550$914f5ff0$%park@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Content-language: ko Content-transfer-encoding: quoted-printable References: <1275380256-15315-1-git-send-email-jy0922.shim@samsung.com> <1276421200.19028.192.camel@localhost> Cc: 'Thomas Gleixner' , linux-mtd@lists.infradead.org Reply-To: kyungmin.park@samsung.com List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, > -----Original Message----- > From: Artem Bityutskiy [mailto:dedekind1@gmail.com] > Sent: Sunday, June 13, 2010 6:27 PM > To: Joonyoung Shim > Cc: linux-mtd@lists.infradead.org; Kyungmin Park; Thomas Gleixner > Subject: Re: [PATCH 1/2] mtd: OneNAND: Add runtime badblock check = feature >=20 > On Tue, 2010-06-01 at 17:17 +0900, Joonyoung Shim wrote: > > From: Kyungmin Park > > > > This patch is to support runtime badblock checking. This supports = only > > OneNAND currently. The OneNAND badblock checking when boots occurs = boot > > time delay. We can reduce boot time because can detect badblock at > > runtime. > > > > Signed-off-by: Kyungmin Park >=20 > Hi, this feature is interesting. But why not to use bad block table > instead of adding more complexity to the already very complex and > difficult to follow code? >=20 > Also, if you really want this, it should be rather lazy checking, = where > you read OOB on demand, and then save this information to the in-ram > BBT, and when you get another ->block_isbad() for a block which was > previously checked, you do not read OOB for the second time. It's based on BBT already. Now I set the BBT values as 0x2 and then = check it at runtime and then mark it 0 for good, 3 for bad block. Right, it's same word lazy checking and runtime check. The original ideas are from UBI scan it read all blocks again at probe. I just scan almost block read once at ubi scan. Thank you, Kyungmin Park >=20 > CCing Thomas, if we are lucky, he'll provide good input. >=20 > -- > Best Regards, > Artem Bityutskiy (=D0=90=D1=80=D1=82=D1=91=D0=BC = =D0=91=D0=B8=D1=82=D1=8E=D1=86=D0=BA=D0=B8=D0=B9)