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=-0.9 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 1C6C0C07E85 for ; Tue, 11 Dec 2018 07:55:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA38D20849 for ; Tue, 11 Dec 2018 07:55:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA38D20849 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 S1726132AbeLKHy7 convert rfc822-to-8bit (ORCPT ); Tue, 11 Dec 2018 02:54:59 -0500 Received: from mail.bootlin.com ([62.4.15.54]:37537 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726036AbeLKHy7 (ORCPT ); Tue, 11 Dec 2018 02:54:59 -0500 Received: by mail.bootlin.com (Postfix, from userid 110) id 4425C20723; Tue, 11 Dec 2018 08:54:56 +0100 (CET) Received: from xps13 (aaubervilliers-681-1-79-44.w90-88.abo.wanadoo.fr [90.88.21.44]) by mail.bootlin.com (Postfix) with ESMTPSA id BF08E20701; Tue, 11 Dec 2018 08:54:45 +0100 (CET) Date: Tue, 11 Dec 2018 08:54:45 +0100 From: Miquel Raynal To: Liang Yang Cc: Boris Brezillon , Jianxin Pan , , Yixun Lan , David Woodhouse , Brian Norris , Marek Vasut , Richard Weinberger , Jerome Brunet , Neil Armstrong , Martin Blumenstingl , Carlo Caione , Kevin Hilman , Rob Herring , Jian Hu , Hanjie Lin , Victor Wan , , , Subject: Re: [PATCH v7 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller Message-ID: <20181211085445.68e57e0e@xps13> In-Reply-To: References: <1542386439-30166-1-git-send-email-jianxin.pan@amlogic.com> <1542386439-30166-3-git-send-email-jianxin.pan@amlogic.com> <20181207102456.1dc67e07@xps13> <823825a3-86fb-9a20-ae29-85cc52d44093@amlogic.com> <20181210123809.5ade45c4@bbrezillon> <79a797c2-f37f-7f7c-e907-2d3c2283ec2d@amlogic.com> <20181210155057.38788656@xps13> Organization: Bootlin X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.32; 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 Liang, Liang Yang wrote on Tue, 11 Dec 2018 09:56:25 +0800: > Hi Miquel, > > On 2018/12/10 22:50, Miquel Raynal wrote: > > Hi Liang, > > > > Liang Yang wrote on Mon, 10 Dec 2018 20:12:39 > > +0800: > > > >> On 2018/12/10 19:38, Boris Brezillon wrote: > >>> On Mon, 10 Dec 2018 19:23:46 +0800 > >>> Liang Yang wrote: > >>> >>>>>> + mtd->ecc_stats.failed++; > >>>>>> + continue; > >>>>>> + } > >>>>>> + mtd->ecc_stats.corrected += ECC_ERR_CNT(*info); > >>>>>> + bitflips = max_t(u32, bitflips, ECC_ERR_CNT(*info)); > >>>>>> + } > >>>>> > >>>>> Are you sure you handle correctly empty pages with bf? > >>>>> >> if scramble is enable, i would say yes here. > >>>> when scramble is disabled, i am considering how to use the helper > >>>> nand_check_erased_ecc_chunk, but it seems that i can't get the ecc > >>>> bytes which is caculated by ecc engine.by the way, nfc dma doesn't send > >>>> out the ecc parity bytes. > >>> > >>> Even if the ECC engine is disabled? > >>> >> No. > >> When ECC engine is disabled, it can read the ecc parity bytes ; but there is another problem that i need to consider how code struct looks better when reading error with ecc opened and then try to raw read. > >> Is there a good idea? > > > > When reading with ECC enabled, in case of uncorrectable error you > > must re-read without ECC, then check if the page is empty or not with > > the core helpers (nand_check_erased_*()). > > > > Is this what you meant? > > > yes. when uncorrectable ECC error, i need firstly read out the ECC bytes without ECC engine and then use the helper nand_check_erased_ecc_chunk to check if blank page. > Of course, the precondition is without scrambler, or the bland page can be detected by meson NFC. A suppose you meant "blank page"? If yes, then you don't need the helper to check for only-0xFF pages. If the controller tells you if the page was blank, then just check for that bit. Thanks, Miquèl