Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755115AbcKNCIB (ORCPT ); Sun, 13 Nov 2016 21:08:01 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46284 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754759AbcKNCG1 (ORCPT ); Sun, 13 Nov 2016 21:06:27 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Karl Beldan" , "Boris Brezillon" , "Brian Norris" Date: Mon, 14 Nov 2016 00:14:07 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 102/152] mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1904 Lines: 51 3.2.84-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Karl Beldan commit f6d7c1b5598b6407c3f1da795dd54acf99c1990c upstream. This fixes subpage writes when using 4-bit HW ECC. There has been numerous reports about ECC errors with devices using this driver for a while. Also the 4-bit ECC has been reported as broken with subpages in [1] and with 16 bits NANDs in the driver and in mach* board files both in mainline and in the vendor BSPs. What I saw with 4-bit ECC on a 16bits NAND (on an LCDK) which got me to try reinitializing the ECC engine: - R/W on whole pages properly generates/checks RS code - try writing the 1st subpage only of a blank page, the subpage is well written and the RS code properly generated, re-reading the same page the HW detects some ECC error, reading the same page again no ECC error is detected Note that the ECC engine is already reinitialized in the 1-bit case. Tested on my LCDK with UBI+UBIFS using subpages. This could potentially get rid of the issue workarounded in [1]. [1] 28c015a9daab ("mtd: davinci-nand: disable subpage write for keystone-nand") Fixes: 6a4123e581b3 ("mtd: nand: davinci_nand, 4-bit ECC for smallpage") Signed-off-by: Karl Beldan Acked-by: Boris Brezillon Signed-off-by: Brian Norris Signed-off-by: Ben Hutchings --- drivers/mtd/nand/davinci_nand.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/mtd/nand/davinci_nand.c +++ b/drivers/mtd/nand/davinci_nand.c @@ -239,6 +239,9 @@ static void nand_davinci_hwctl_4bit(stru unsigned long flags; u32 val; + /* Reset ECC hardware */ + davinci_nand_readl(info, NAND_4BIT_ECC1_OFFSET); + spin_lock_irqsave(&davinci_nand_lock, flags); /* Start 4-bit ECC calculation for read/write */