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 A6A42C07E85 for ; Tue, 11 Dec 2018 09:07:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 74E0620849 for ; Tue, 11 Dec 2018 09:07:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 74E0620849 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 S1726209AbeLKJHc convert rfc822-to-8bit (ORCPT ); Tue, 11 Dec 2018 04:07:32 -0500 Received: from mail.bootlin.com ([62.4.15.54]:39777 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726085AbeLKJHb (ORCPT ); Tue, 11 Dec 2018 04:07:31 -0500 Received: by mail.bootlin.com (Postfix, from userid 110) id CD42320862; Tue, 11 Dec 2018 10:07:28 +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 504AC20723; Tue, 11 Dec 2018 10:07:18 +0100 (CET) Date: Tue, 11 Dec 2018 10:07:18 +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: <20181211100718.51d2cd6c@xps13> In-Reply-To: <356aed95-518d-7cd0-4337-184f181472ad@amlogic.com> 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> <20181211085445.68e57e0e@xps13> <356aed95-518d-7cd0-4337-184f181472ad@amlogic.com> 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 16:36:47 +0800: > Hi Miquel, > > Thanks for your quickly reply. > > On 2018/12/11 15:54, Miquel Raynal wrote: > > 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. > > > > i think not. we need to return back the previous problem that how i can get the bitflips of one blank page. i think i need the helper. You are right, I suppose the "blank page" flag is only triggered if there is no bitflip. In this case you can assume there are no bitflips. Otherwise the controller will trigger an uncorrectable error event and you will have to re-read the page without ECC and check for bitflips with the helper. Thanks, Miquèl