From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5D5C4C3279B for ; Sun, 8 Jul 2018 21:47:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22A7420837 for ; Sun, 8 Jul 2018 21:47:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 22A7420837 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933060AbeGHVrq convert rfc822-to-8bit (ORCPT ); Sun, 8 Jul 2018 17:47:46 -0400 Received: from mail.bootlin.com ([62.4.15.54]:38056 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754371AbeGHVro (ORCPT ); Sun, 8 Jul 2018 17:47:44 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id 449002079C; Sun, 8 Jul 2018 23:47:42 +0200 (CEST) Received: from xps13 (unknown [91.224.148.103]) by mail.bootlin.com (Postfix) with ESMTPSA id 9E5B1203B4; Sun, 8 Jul 2018 23:47:41 +0200 (CEST) Date: Sun, 8 Jul 2018 23:47:42 +0200 From: Miquel Raynal To: Abhishek Sahu Cc: David Woodhouse , Boris Brezillon , Brian Norris , Marek Vasut , Richard Weinberger , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, Andy Gross , Archit Taneja Subject: Re: [PATCH v5] mtd: rawnand: qcom: erased page bitflips detection Message-ID: <20180708234742.0d86b9d1@xps13> In-Reply-To: <1530619563-24712-1-git-send-email-absahu@codeaurora.org> References: <1530619563-24712-1-git-send-email-absahu@codeaurora.org> Organization: Bootlin X-Mailer: Claws Mail 3.15.0-dirty (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Abhishek, Abhishek Sahu wrote on Tue, 3 Jul 2018 17:36:03 +0530: > NAND parts can have bitflips in an erased page due to the > process technology used. In this case, QCOM NAND controller > is not able to identify that page as an erased page. > Currently the driver calls nand_check_erased_ecc_chunk() for > identifying the erased pages but this won’t work always since the > checking is being with ECC engine returned data. In case of > bitflips, the ECC engine tries to correct the data and then it > generates the uncorrectable error. Now, this data is not equal to > original raw data. For erased CW identification, the raw data > should be read again from NAND device and this > nand_check_erased_ecc_chunk function() should be called for raw > data only. > > Now following logic is being added to identify the erased > codeword bitflips. > > 1. In most of the cases, not all the codewords will have bitflips > and only single CW will have bitflips. So, there is no need to > read the complete raw page data. The NAND raw read can be > scheduled for any CW in page. The NAND controller works on CW > basis and it will update the status register after each CW read. > Maintain the bitmask for the CW which generated the uncorrectable > error. > 2. Do raw read for all the CW's which generated the uncorrectable > error. > 3. Both DATA and OOB need to be checked for number of 0. The > top-level API can be called with only data buf or OOB buf so use > chip->databuf if data buf is null and chip->oob_poi if > OOB buf is null for copying the raw bytes temporarily. > 4. For each CW, check the number of 0 in cw_data and usable > oob bytes, The bbm and spare (unused) bytes bit flip won’t > affect the ECC so don’t check the number of bitflips in this area. > > Signed-off-by: Abhishek Sahu > --- > * Changes from v4: > > 1. Used for_each_set_bit for determining CW’s which generated > uncorrectable errors. > 2. Introduced cw_data_buf and cw_oob_buf which will have starting > buffer address for current codeword and used the same in helper > functions. > 3. Added new line before calling of nand_check_erased_ecc_chunk for > better code readability. > > * Changes from v3: > > 1. Major changes in erased codeword detection for > raw read function > > * Changes from v2: > NONE > > * Changes from v1: > 1. Minor change in commit message > 2. invalidate pagebuf if databuf or oob_poi is used > > drivers/mtd/nand/raw/qcom_nandc.c | 126 +++++++++++++++++++++++++++----------- > 1 file changed, 89 insertions(+), 37 deletions(-) Applied to nand/next. Thanks, Miquèl