From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751188AbeEBKZ7 (ORCPT ); Wed, 2 May 2018 06:25:59 -0400 Received: from mail.bootlin.com ([62.4.15.54]:45463 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750849AbeEBKZ5 (ORCPT ); Wed, 2 May 2018 06:25:57 -0400 Date: Wed, 2 May 2018 12:25:45 +0200 From: Boris Brezillon To: Jane Wan Cc: dwmw2@infradead.org, computersforpeace@gmail.com, ties.bos@nokia.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] Use bit-wise majority to recover the contents of ONFI parameter Message-ID: <20180502122545.6bd28c3b@bbrezillon> In-Reply-To: <1524788396-32380-3-git-send-email-Jane.Wan@nokia.com> References: <1524788396-32380-1-git-send-email-Jane.Wan@nokia.com> <1524788396-32380-3-git-send-email-Jane.Wan@nokia.com> 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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jane, On Thu, 26 Apr 2018 17:19:56 -0700 Jane Wan wrote: > Signed-off-by: Jane Wan > --- > drivers/mtd/nand/nand_base.c | 35 +++++++++++++++++++++++++++++++---- > 1 file changed, 31 insertions(+), 4 deletions(-) > > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c > index c2e1232..161b523 100644 > --- a/drivers/mtd/nand/nand_base.c > +++ b/drivers/mtd/nand/nand_base.c > @@ -3153,8 +3153,10 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip, > int *busw) > { > struct nand_onfi_params *p = &chip->onfi_params; > - int i, j; > - int val; > + int i, j, k, len, val; > + uint8_t copy[3][256], v8; > + > + len = (sizeof(*p) > 256) ? 256 : sizeof(*p); > > /* Try ONFI for unknown chip or LP */ > chip->cmdfunc(mtd, NAND_CMD_READID, 0x20, -1); > @@ -3170,11 +3172,36 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip, > le16_to_cpu(p->crc)) { > break; > } > + pr_err("CRC of parameter page %d is not valid\n", i); > + for (j = 0; j < len; j++) > + copy[i][j] = ((uint8_t *)p)[j]; > } > > if (i == 3) { > - pr_err("Could not find valid ONFI parameter page; aborting\n"); > - return 0; > + pr_err("Could not find valid ONFI parameter page\n"); > + pr_info("Recover ONFI parameters with bit-wise majority\n"); > + for (j = 0; j < len; j++) { > + if (copy[0][j] == copy[1][j] || > + copy[0][j] == copy[2][j]) { > + ((uint8_t *)p)[j] = copy[0][j]; > + } else if (copy[1][j] == copy[2][j]) { > + ((uint8_t *)p)[j] = copy[1][j]; > + } else { > + ((uint8_t *)p)[j] = 0; > + for (k = 0; k < 8; k++) { > + v8 = (copy[0][j] >> k) & 0x1; > + v8 += (copy[1][j] >> k) & 0x1; > + v8 += (copy[2][j] >> k) & 0x1; > + if (v8 > 1) > + ((uint8_t *)p)[j] |= (1 << k); > + } > + } > + } I'd like this bit-wise majority algorithm to be generic and moved to nand_base.c, because we might want to do the same in the core and make it work for any number of repetitions of the PARAM page. > + if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) != > + le16_to_cpu(p->crc)) { > + pr_err("ONFI parameter recovery failed, aborting\n"); > + return 0; > + } > } > > /* Check version */ Thanks, Boris