mtd: at91: atmel_nand: return bit flips for the PMECC read_page()

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 <josh.wu@atmel.com>
Reviewed-by: Mike Dunn <mikedunn@newsguy.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index c918386..1669d27 100644 (file)
--- 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,