From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934895AbeEIOTl (ORCPT ); Wed, 9 May 2018 10:19:41 -0400 Received: from mail.bootlin.com ([62.4.15.54]:59714 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932701AbeEIOTk (ORCPT ); Wed, 9 May 2018 10:19:40 -0400 Date: Wed, 9 May 2018 16:19:28 +0200 From: Boris Brezillon To: Jane Wan Cc: miquel.raynal@bootlin.com, dwmw2@infradead.org, computersforpeace@gmail.com, richard@nod.at, marek.vasut@gmail.com, yamada.masahiro@socionext.com, prabhakar.kushwaha@nxp.com, shawnguo@kernel.org, jagdish.gediya@nxp.com, shreeya.patel23498@gmail.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, ties.bos@nokia.com Subject: Re: [PATCH v4 2/2] mtd: rawnand: use bit-wise majority to recover the contents of ONFI parameter Message-ID: <20180509161928.149a42a7@bbrezillon> In-Reply-To: <1525814394-30067-2-git-send-email-Jane.Wan@nokia.com> References: <1525814394-30067-1-git-send-email-Jane.Wan@nokia.com> <1525814394-30067-2-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 On Tue, 8 May 2018 14:19:54 -0700 Jane Wan wrote: > Per ONFI specification (Rev. 4.0), if all parameter pages have invalid > CRC values, the bit-wise majority may be used to recover the contents of > the parameter pages from the parameter page copies present. > > Signed-off-by: Jane Wan > --- > drivers/mtd/nand/raw/nand_base.c | 49 ++++++++++++++++++++++++++++++++++---- > 1 file changed, 44 insertions(+), 5 deletions(-) > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c > index 72f3a89..dfc341c 100644 > --- a/drivers/mtd/nand/raw/nand_base.c > +++ b/drivers/mtd/nand/raw/nand_base.c > @@ -5086,6 +5086,38 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip, > return ret; > } > > +#define GET_BIT(bit, val) (((val) >> (bit)) & 0x01) > + > +/* > + * Recover NAND parameter page with bit-wise majority > + */ > +static int onfi_recover_param(struct nand_onfi_params *p, int pages) I had something more generic in mind: static void nand_bit_wise_majority(const void **srcbufs, void *dstbuf, unsigned int nbufs, unsigned int bufsize) { ... } And then you do the crc check in nand_flash_detect_onfi(). The reason I'm asking that is because I'm almost sure we'll re-use this functions for extended param pages, and also for vendor specific data (we already have a byte-wise majority check in the hynix driver, so I wouldn't be surprised if other vendors decided to use a bit-wise approach for some of their OTP area). > +{ > + int i, j, k; > + u8 v, m; > + u8 *buf; > + > + buf = (u8 *)p; > + for (i = 0; i < sizeof(*p); i++) { > + v = 0; > + for (j = 0; j < 8; j++) { > + m = 0; > + for (k = 0; k < pages; k++) > + m += GET_BIT(j, buf[k*sizeof(*p) + i]); > + if (m > pages/2) > + v |= BIT(j); > + } > + ((u8 *)p)[i] = v; > + } > + > + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)p, 254) == > + le16_to_cpu(p->crc)) { > + return 1; > + } > + > + return 0; > +} > + > /* > * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise. > */ > @@ -5102,7 +5134,7 @@ static int nand_flash_detect_onfi(struct nand_chip *chip) > return 0; > > /* ONFI chip: allocate a buffer to hold its parameter page */ > - p = kzalloc(sizeof(*p), GFP_KERNEL); > + p = kzalloc((sizeof(*p) * 3), GFP_KERNEL); > if (!p) > return -ENOMEM; > > @@ -5113,21 +5145,28 @@ static int nand_flash_detect_onfi(struct nand_chip *chip) > } > > for (i = 0; i < 3; i++) { > - ret = nand_read_data_op(chip, p, sizeof(*p), true); > + ret = nand_read_data_op(chip, &p[i], sizeof(*p), true); > if (ret) { > ret = 0; > goto free_onfi_param_page; > } > > - if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) == > + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)&p[i], 254) == > le16_to_cpu(p->crc)) { > + if (i) > + memcpy(p, &p[i], sizeof(*p)); > break; > } > } > > if (i == 3) { > - pr_err("Could not find valid ONFI parameter page; aborting\n"); > - goto free_onfi_param_page; > + pr_err("Could not find valid ONFI parameter page\n"); > + pr_info("Recover ONFI params with bit-wise majority\n"); > + ret = onfi_recover_param(p, 3); > + if (ret == 0) { > + pr_err("ONFI parameter recovery failed, aborting\n"); > + goto free_onfi_param_page; > + } > } > > /* Check version */