From patchwork Tue Nov 27 10:50:31 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [v2] MTD: at91: atmel_nand: return bit flips for the PMECC read_page() From: "Wu, Josh" X-Patchwork-Id: 202252 Message-Id: <1354013431-13598-1-git-send-email-josh.wu@atmel.com> To: linux-mtd@lists.infradead.org, linux-arm-kernel@lists.infradead.org, dedekind1@gmail.com Cc: nicolas.ferre@atmel.com, mikedunn@newsguy.com, plagnioj@jcrosoft.com, Josh Wu Date: Tue, 27 Nov 2012 18:50:31 +0800 This patch fix pmecc's read_page() to return maximum number of bitflips, 0 if uncorrectable. In the commit: 3f91e94f7f511de74c0d2abe08672ccdbdd1961c ("mtd: nand: read_page() returns max_bitflips ()"), The ecc.read_page() is changed to return the maximum number of bitflips. And when meet uncorrectable bitflips it needs to return 0. See the comment in nand.h: * @read_page: function to read a page according to the ECC generator * requirements; returns maximum number of bitflips corrected in * any single ECC step, 0 if bitflips uncorrectable, -EIO hw error Signed-off-by: Josh Wu Reviewed-by: Mike Dunn --- change since v1: 1. add detail commit message for the fix. 2. return 0 when meet uncorrectable bitflips according to Mike Dunn's suggestion. drivers/mtd/nand/atmel_nand.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c index c918386..1669d27 100644 --- a/drivers/mtd/nand/atmel_nand.c +++ b/drivers/mtd/nand/atmel_nand.c @@ -723,6 +723,7 @@ static int pmecc_correction(struct mtd_info *mtd, u32 pmecc_stat, uint8_t *buf, struct atmel_nand_host *host = nand_chip->priv; int i, err_nbr, eccbytes; uint8_t *buf_pos; + int total_err = 0; eccbytes = nand_chip->ecc.bytes; for (i = 0; i < eccbytes; i++) @@ -750,12 +751,13 @@ normal_check: pmecc_correct_data(mtd, buf_pos, ecc, i, host->pmecc_bytes_per_sector, err_nbr); mtd->ecc_stats.corrected += err_nbr; + total_err += err_nbr; } } pmecc_stat >>= 1; } - return 0; + return total_err; } static int atmel_nand_pmecc_read_page(struct mtd_info *mtd, @@ -767,6 +769,7 @@ static int atmel_nand_pmecc_read_page(struct mtd_info *mtd, uint32_t *eccpos = chip->ecc.layout->eccpos; uint32_t stat; unsigned long end_time; + int bitflips = 0; pmecc_writel(host->ecc, CTRL, PMECC_CTRL_RST); pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DISABLE); @@ -789,11 +792,14 @@ static int atmel_nand_pmecc_read_page(struct mtd_info *mtd, } stat = pmecc_readl_relaxed(host->ecc, ISR); - if (stat != 0) - if (pmecc_correction(mtd, stat, buf, &oob[eccpos[0]]) != 0) - return -EIO; + if (stat != 0) { + bitflips = pmecc_correction(mtd, stat, buf, &oob[eccpos[0]]); + if (bitflips < 0) + /* uncorrectable errors */ + return 0; + } - return 0; + return bitflips; } static int atmel_nand_pmecc_write_page(struct mtd_info *mtd,