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 B8403C43141 for ; Thu, 21 Jun 2018 11:16:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D3A420883 for ; Thu, 21 Jun 2018 11:16:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D3A420883 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 S1754374AbeFULQl (ORCPT ); Thu, 21 Jun 2018 07:16:41 -0400 Received: from mail.bootlin.com ([62.4.15.54]:50658 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754178AbeFULQk (ORCPT ); Thu, 21 Jun 2018 07:16:40 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id 6D3112072C; Thu, 21 Jun 2018 13:16:38 +0200 (CEST) Received: from bbrezillon (AAubervilliers-681-1-50-153.w90-88.abo.wanadoo.fr [90.88.168.153]) by mail.bootlin.com (Postfix) with ESMTPSA id 24B72206D8; Thu, 21 Jun 2018 13:16:28 +0200 (CEST) Date: Thu, 21 Jun 2018 13:16:28 +0200 From: Boris Brezillon To: Chris Packham Cc: miquel.raynal@bootlin.com, dwmw2@infradead.org, computersforpeace@gmail.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, Richard Weinberger , Marek Vasut Subject: Re: [PATCH v4 5/6] mtd: rawnand: micron: support 8/512 on-die ECC Message-ID: <20180621131628.07220d31@bbrezillon> In-Reply-To: <20180621103328.28206-6-chris.packham@alliedtelesis.co.nz> References: <20180621103328.28206-1-chris.packham@alliedtelesis.co.nz> <20180621103328.28206-6-chris.packham@alliedtelesis.co.nz> 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=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 21 Jun 2018 22:33:27 +1200 Chris Packham wrote: > Micron MT29F1G08ABAFAWP-ITE:F supports an on-die ECC with 8 bits > per 512 bytes. Add support for this combination. > > Signed-off-by: Chris Packham > --- > Changes in v2: > - New > Changes in v3: > - Handle reporting of corrected errors that don't require a rewrite, expand > comment for the ECC status bits. > Changes in v4: > - Use a switch statement for handling ECC status > - Update ecc_stats.corrected > > drivers/mtd/nand/raw/nand_micron.c | 68 ++++++++++++++++++++---------- > 1 file changed, 46 insertions(+), 22 deletions(-) > > diff --git a/drivers/mtd/nand/raw/nand_micron.c b/drivers/mtd/nand/raw/nand_micron.c > index d30bd4df9b12..f1ecd4986b50 100644 > --- a/drivers/mtd/nand/raw/nand_micron.c > +++ b/drivers/mtd/nand/raw/nand_micron.c > @@ -18,10 +18,28 @@ > #include > > /* > - * Special Micron status bit that indicates when the block has been > - * corrected by on-die ECC and should be rewritten > + * Special Micron status bit 3 indicates that the block has been > + * corrected by on-die ECC and should be rewritten. > + * > + * On chips with 8-bit ECC and additional bit can be used to distinguish > + * cases where a errors were corrected without needing a rewrite > + * > + * Bit 4 Bit 3 Bit 0 Description > + * ----- ----- ----- ----------- > + * 0 0 0 No Errors > + * 0 0 1 Multiple uncorrected errors > + * 0 1 0 4 - 6 errors corrected, recommend rewrite > + * 0 1 1 Reserved > + * 1 0 0 1 - 3 errors corrected > + * 1 0 1 Reserved > + * 1 1 0 7 - 8 errors corrected, recommend rewrite > */ > -#define NAND_STATUS_WRITE_RECOMMENDED BIT(3) > +#define NAND_STATUS_MASK (BIT(4) | BIT(3) | BIT(0)) > +#define NAND_STATUS_NO_ERRORS 0 > +#define NAND_STATUS_UNCORRECTABLE BIT(0) > +#define NAND_STATUS_4_6_CORRECTED BIT(3) > +#define NAND_STATUS_1_3_CORRECTED BIT(4) > +#define NAND_STATUS_7_8_CORRECTED (BIT(4) | BIT(3)) NAND_ECC_STATUS_ prefix would be better than NAND_STATUS_ > > struct nand_onfi_vendor_micron { > u8 two_plane_read; > @@ -137,18 +155,31 @@ micron_nand_read_page_on_die_ecc(struct mtd_info *mtd, struct nand_chip *chip, > if (ret) > goto out; > > - if (status & NAND_STATUS_FAIL) { > + /* > + * The internal ECC doesn't tell us the number of bitflips > + * that have been corrected, but tells us if it recommends to > + * rewrite the block. If it's the case, then we pretend we had > + * a number of bitflips equal to the ECC strength, which will > + * hint the NAND core to rewrite the block. > + */ > + switch (status & NAND_STATUS_MASK) { > + case NAND_STATUS_UNCORRECTABLE: I'd recommend handling 8bit and 4bit on-die ECC separately (create on subfunction per kind of ECC), and not using the same _MASK, just in case unused bits value have a different meaning or are simply not set to 0 by default. > mtd->ecc_stats.failed++; > - } else if (status & NAND_STATUS_WRITE_RECOMMENDED) { > - /* > - * The internal ECC doesn't tell us the number of bitflips > - * that have been corrected, but tells us if it recommends to > - * rewrite the block. If it's the case, then we pretend we had > - * a number of bitflips equal to the ECC strength, which will > - * hint the NAND core to rewrite the block. > - */ > - mtd->ecc_stats.corrected += chip->ecc.strength; > + break; > + case NAND_STATUS_1_3_CORRECTED: > + mtd->ecc_stats.corrected++; > + max_bitflips = 1; Should you always take the max of the range, so here: mtd->ecc_stats.corrected += 3; max_bitflips = 3; > + break; > + case NAND_STATUS_4_6_CORRECTED: > + mtd->ecc_stats.corrected += 4; += 6; > + /* rewrite recommended */ > + max_bitflips = chip->ecc.strength; Here it should be 6, not chip->ecc.strength. > + break; > + case NAND_STATUS_7_8_CORRECTED: > + mtd->ecc_stats.corrected += 7; += 8; > + /* rewrite recommended */ > max_bitflips = chip->ecc.strength; > + break; > } > > ret = nand_read_data_op(chip, buf, mtd->writesize, false); > @@ -239,13 +270,6 @@ static int micron_supports_on_die_ecc(struct nand_chip *chip) > if (feature[0] & ONFI_FEATURE_ON_DIE_ECC_EN) > return MICRON_ON_DIE_MANDATORY; > > - /* > - * Some Micron NANDs have an on-die ECC of 4/512, some other > - * 8/512. We only support the former. > - */ > - if (chip->ecc_strength_ds != 4) > - return MICRON_ON_DIE_UNSUPPORTED; I'd prefer to keep an explicit check here rather than accepting everything. See how 8 and 4 bit ECC differ, it's likely to be the case if Micron ever has a 16bit ECC. > - > return MICRON_ON_DIE_SUPPORTED; > } > > @@ -275,9 +299,9 @@ static int micron_nand_init(struct nand_chip *chip) > return -EINVAL; > } > > - chip->ecc.bytes = 8; > + chip->ecc.bytes = chip->ecc_strength_ds * 2; > chip->ecc.size = 512; > - chip->ecc.strength = 4; > + chip->ecc.strength = chip->ecc_strength_ds; > chip->ecc.algo = NAND_ECC_BCH; > chip->ecc.read_page = micron_nand_read_page_on_die_ecc; > chip->ecc.write_page = micron_nand_write_page_on_die_ecc;