Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932880AbbENJnO (ORCPT ); Thu, 14 May 2015 05:43:14 -0400 Received: from a.ns.miles-group.at ([95.130.255.143]:65275 "EHLO radon.swed.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932484AbbENJnM (ORCPT ); Thu, 14 May 2015 05:43:12 -0400 Message-ID: <55546E27.6000909@nod.at> Date: Thu, 14 May 2015 11:43:03 +0200 From: Richard Weinberger User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Ben Shelton , dwmw2@infradead.org, computersforpeace@gmail.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, dedekind1@gmail.com CC: Jeff Westfahl Subject: Re: [PATCH 2/3] mtd: nand: implement 'max_bad_blocks' mtd function References: <1431357596-29959-1-git-send-email-ben.shelton@ni.com> <1431357596-29959-3-git-send-email-ben.shelton@ni.com> In-Reply-To: <1431357596-29959-3-git-send-email-ben.shelton@ni.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2758 Lines: 70 Am 11.05.2015 um 17:19 schrieb Ben Shelton: > From: Jeff Westfahl > > Implement the new mtd function 'max_bad_blocks'. Use the "bad blocks > maximum per LUN" field in the ONFI parameter page to find the maximum > number of bad blocks to reserve for an MTD, taking into account the > number of LUNs in the NAND device and how many LUNs the MTD spans. > > From the ONFI 1.0 spec: "This field contains the maximum number of > blocks that may be defective at manufacture and over the life of the > device per LUN. The maximum rating assumes that the host is following > the block endurance requirements and the ECC requirements reported in > the parameter page." > > Signed-off-by: Jeff Westfahl > --- > drivers/mtd/nand/nand_base.c | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c > index c2e1232..a97d08e 100644 > --- a/drivers/mtd/nand/nand_base.c > +++ b/drivers/mtd/nand/nand_base.c > @@ -2884,6 +2884,40 @@ static int nand_block_markbad(struct mtd_info *mtd, loff_t ofs) > } > > /** > + * nand_max_bad_blocks - [MTD Interface] Max number of bad blocks for an mtd > + * @mtd: MTD device structure > + * @ofs: offset relative to mtd start > + * @len: length of mtd > + */ > +static int nand_max_bad_blocks(struct mtd_info *mtd, loff_t ofs, size_t len) > +{ > + struct nand_chip *chip = mtd->priv; > + uint32_t part_start_block; > + uint32_t part_end_block; > + uint32_t part_start_lun; > + uint32_t part_end_lun; > + > + /* ONFI is used to determine the maximum bad block count. */ > + if (!chip->onfi_version) > + return -ENOTSUPP; > + > + /* Get the start and end of the partition in erase blocks. */ > + part_start_block = mtd_div_by_eb(ofs, mtd); > + part_end_block = mtd_div_by_eb(len, mtd) + part_start_block - 1; > + > + /* Get the start and end LUNs of the partition. */ > + part_start_lun = part_start_block / chip->onfi_params.blocks_per_lun; > + part_end_lun = part_end_block / chip->onfi_params.blocks_per_lun; > + > + /* > + * Look up the bad blocks per unit and multiply by the number of units > + * that the partition spans. > + */ > + return chip->onfi_params.bb_per_lun * > + (part_end_lun - part_start_lun + 1); Hmm, doesn't that calculation assume that all bad blocks are uniformly distributed across the whole chip? Not sure if is a good idea to focus on the best case. Currently UBI assumes the worst case. Thanks, //richard -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/