From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.bootlin.com ([62.4.15.54]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fCOcu-0003p1-VN for linux-mtd@lists.infradead.org; Sat, 28 Apr 2018 12:06:55 +0000 Date: Sat, 28 Apr 2018 14:06:38 +0200 From: Miquel Raynal To: Jane Wan Cc: dwmw2@infradead.org, computersforpeace@gmail.com, ties.bos@nokia.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, Boris Brezillon Subject: Re: [PATCH 2/2] Use bit-wise majority to recover the contents of ONFI parameter Message-ID: <20180428140638.2e2c04dd@xps13> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Jane, Same comments as before, please: get the right maintainers, add a commit log, rebase and fix the title prefix. Have you ever needed/tried this algorithm before?=20 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(-) >=20 > 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 =3D &chip->onfi_params; > - int i, j; > - int val; > + int i, j, k, len, val; > + uint8_t copy[3][256], v8; Please use u8 instead of uint8_t (./scripts/checkpatch.pl --strict will give you the list of styling issues to fix. I don't think you should allocate that much space on the stack, please use dynamic allocation. > + > + len =3D (sizeof(*p) > 256) ? 256 : sizeof(*p); This is a maximum derivation, there are helpers for that. I am not sure this is relevant, won't you read only 256 bytes anyway? > =20 > /* 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; > } Space. > + pr_err("CRC of parameter page %d is not valid\n", i); > + for (j =3D 0; j < len; j++) > + copy[i][j] =3D ((uint8_t *)p)[j]; 'copy' is maybe not a meaningful name. > } > =20 > if (i =3D=3D 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 =3D 0; j < len; j++) { > + if (copy[0][j] =3D=3D copy[1][j] || > + copy[0][j] =3D=3D copy[2][j]) { > + ((uint8_t *)p)[j] =3D copy[0][j]; > + } else if (copy[1][j] =3D=3D copy[2][j]) { > + ((uint8_t *)p)[j] =3D copy[1][j]; > + } else { > + ((uint8_t *)p)[j] =3D 0; > + for (k =3D 0; k < 8; k++) { > + v8 =3D (copy[0][j] >> k) & 0x1; v8 could be declared in the else statement of in the for loop. The name could also be changed. > + v8 +=3D (copy[1][j] >> k) & 0x1; > + v8 +=3D (copy[2][j] >> k) & 0x1; > + if (v8 > 1) > + ((uint8_t *)p)[j] |=3D (1 << k); Please use the BIT() macro. > + } > + } > + } Space. > + if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) !=3D > + le16_to_cpu(p->crc)) { > + pr_err("ONFI parameter recovery failed, aborting\n"); > + return 0; > + } > } > =20 > /* Check version */ Thanks, Miqu=C3=A8l --=20 Miquel Raynal, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com