From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pa0-x243.google.com ([2607:f8b0:400e:c03::243]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1bB7LT-0004at-6K for linux-mtd@lists.infradead.org; Thu, 09 Jun 2016 21:18:31 +0000 Received: by mail-pa0-x243.google.com with SMTP id fg1so3546518pad.3 for ; Thu, 09 Jun 2016 14:18:10 -0700 (PDT) From: Kamal Dasu To: linux-mtd@lists.infradead.org, computersforpeace@gmail.com, boris.brezillon@free-electrons.com Cc: f.fainelli@gmail.com, bcm-kernel-feedback-list@broadcom.com, Kamal Dasu Subject: [V3, 1/2] mtd: brcmnand: Add check for erased page bitflips Date: Thu, 9 Jun 2016 17:17:54 -0400 Message-Id: <1465507075-9447-1-git-send-email-kdasu.kdev@gmail.com> List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Check for erased page bitflips in a page. And if well within threshold return data as all 0xff. Apply sw check for controller version < 7.2. Controller vesion >= 7.2 has hw support. Signed-off-by: Kamal Dasu --- V3 changes Return the max bitflips from a sector within a page V2 changes Added use of nand_check_erased_ecc_chunk Restrict change to older controller < 7.2 --- drivers/mtd/nand/brcmnand/brcmnand.c | 62 ++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c index b76ad7c..7ee9617 100644 --- a/drivers/mtd/nand/brcmnand/brcmnand.c +++ b/drivers/mtd/nand/brcmnand/brcmnand.c @@ -1545,6 +1545,56 @@ static int brcmnand_read_by_pio(struct mtd_info *mtd, struct nand_chip *chip, return ret; } +/* + * Check a page to see if it is erased (w/ bitflips) after an uncorrectable ECC + * error + * + * Because the HW ECC signals an ECC error if an erase paged has even a single + * bitflip, we must check each ECC error to see if it is actually an erased + * page with bitflips, not a truly corrupted page. + * + * On a real error, return a negative error code (-EBADMSG for ECC error), and + * buf will contain raw data. + * Otherwise, buf gets filled with 0xffs and return the maximum number of + * bitflips-per-ECC-sector to the caller. + * + */ +static int brcmstb_nand_verify_erased_page(struct mtd_info *mtd, + struct nand_chip *chip, void *buf, u64 addr) +{ + int i, sas; + void *oob = chip->oob_poi; + int bitflips = 0; + int page = addr >> chip->page_shift; + int ret; + + if (!buf) { + buf = chip->buffers->databuf; + /* Invalidate page cache */ + chip->pagebuf = -1; + } + + sas = mtd->oobsize / chip->ecc.steps; + + /* read without ecc for verification */ + chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page); + ret = chip->ecc.read_page_raw(mtd, chip, buf, true, page); + if (ret) + return ret; + + for (i = 0; i < chip->ecc.steps; i++, oob += sas) { + ret = nand_check_erased_ecc_chunk(buf, chip->ecc.size, + oob, sas, NULL, 0, + chip->ecc.strength); + if (ret < 0) + return ret; + + bitflips = max(bitflips, ret); + } + + return bitflips; +} + static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip, u64 addr, unsigned int trans, u32 *buf, u8 *oob) { @@ -1575,6 +1625,18 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip, } if (mtd_is_eccerr(err)) { + /* + * Controller version 7.2 has hw encoder to detect erased page + * bitflips, apply sw verification for older controllers only + */ + if (ctrl->nand_version < 0x0702) { + err = brcmstb_nand_verify_erased_page(mtd, chip, buf, + addr); + /* erased page bitflips corrected */ + if (err > 0) + return err; + } + dev_dbg(ctrl->dev, "uncorrectable error at 0x%llx\n", (unsigned long long)err_addr); mtd->ecc_stats.failed++; -- 1.9.1