From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from co202.xi-lite.net ([149.6.83.202]) by canuck.infradead.org with esmtp (Exim 4.72 #1 (Red Hat Linux)) id 1PsXfQ-000180-R3 for linux-mtd@lists.infradead.org; Thu, 24 Feb 2011 09:39:25 +0000 Date: Thu, 24 Feb 2011 10:38:00 +0100 From: Ivan Djelic To: Viresh Kumar Subject: Re: [PATCH] Newly erased page read workaround Message-ID: <20110224093800.GA7880@parrot.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: Cc: Vipin Kumar , "Artem.Bityutskiy@nokia.com" , "linux-mtd@lists.infradead.org" , "David.Woodhouse@intel.com" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Feb 24, 2011 at 06:10:16AM +0000, Viresh Kumar wrote: > From: Vipin Kumar > > A newly erased page contains ff in data as well as spare area. While reading an > erased page, the read out ecc from spare area does not match the ecc generated > by fsmc ecc hardware accelarator. This is because ecc of data ff ff is not ff > ff. This leads to errors when jffs2 fs erases and reads back the pages to > ensure consistency. > > This patch adds a software workaround to ensure that the ecc check is not > performed for erased pages. An erased page is checked by checking data as ff ff. Hello Vipin, Just a suggestion: maybe you could mention in your comments the fact that you cannot workaround the problem using a mask to get a valid ECC on erased pages, because your controller does not allow it ? If you plan to use your workaround on recent NAND devices with UBIFS, you may still experience problems because of uncorrected bitflips on erased pages, and get errors such as: UBIFS error (pid 576): ubifs_scan: corrupt empty space at LEB 509:126586 UBIFS error (pid 576): ubifs_scanned_corruption: corruption at LEB 509:126586 UBIFS error (pid 576): ubifs_scan: LEB 509 scanning failed UBIFS warning (pid 576): ubifs_ro_mode: switched to read-only mode, error -117 Regards, Ivan