mtd: nand: read_page() returns max_bitflips

The ecc.read_page() method for nand drivers is changed to return the maximum
number of bitflips that were corrected on any one region covering an ecc step,
This patch doesn't change what the nand code returns to mtd.

This v2 includes the change to the fsl_ifc_nand driver requested by Scott¹.

¹ http://lists.infradead.org/pipermail/linux-mtd/2012-April/040883.html

Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Acked-by (freescale changes): Scott Wood <scottwood@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/nand/fsmc_nand.c b/drivers/mtd/nand/fsmc_nand.c
index 9d7f417..6bf59fd 100644
--- a/drivers/mtd/nand/fsmc_nand.c
+++ b/drivers/mtd/nand/fsmc_nand.c
@@ -720,6 +720,7 @@
 	 */
 	uint16_t ecc_oob[7];
 	uint8_t *oob = (uint8_t *)&ecc_oob[0];
+	unsigned int max_bitflips = 0;
 
 	for (i = 0, s = 0; s < eccsteps; s++, i += eccbytes, p += eccsize) {
 		chip->cmdfunc(mtd, NAND_CMD_READ0, s * eccsize, page);
@@ -748,13 +749,15 @@
 		chip->ecc.calculate(mtd, p, &ecc_calc[i]);
 
 		stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
-		if (stat < 0)
+		if (stat < 0) {
 			mtd->ecc_stats.failed++;
-		else
+		} else {
 			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
 	}
 
-	return 0;
+	return max_bitflips;
 }
 
 /*