mtd: nand: add sanity check of ecc strength to nand_scan_tail()

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=e2788c98b98269a3131bffd2b57599280d7abd73
Commit:     e2788c98b98269a3131bffd2b57599280d7abd73
Parent:     3f91e94f7f511de74c0d2abe08672ccdbdd1961c
Author:     Mike Dunn <mikedunn at newsguy.com>
AuthorDate: Wed Apr 25 12:06:10 2012 -0700
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Sun May 13 23:12:41 2012 -0500

    mtd: nand: add sanity check of ecc strength to nand_scan_tail()
    
    This patch adds sanity checks that ensure that drivers for controllers with
    hardware ECC set the 'strength' element in struct nand_ecc_ctrl.  Also stylistic
    changes to the line that calculates strength for software ECC.
    
    This v2 simplifies the check.  Thanks Brian!¹
    
    ¹ http://lists.infradead.org/pipermail/linux-mtd/2012-April/040890.html
    
    Signed-off-by: Mike Dunn <mikedunn at newsguy.com>
    Acked-by: Brian Norris <computersforpeace at gmail.com>
    Signed-off-by: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/nand/nand_base.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 8718eaf..9f5d339 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3348,8 +3348,13 @@ int nand_scan_tail(struct mtd_info *mtd)
 		if (!chip->ecc.write_oob)
 			chip->ecc.write_oob = nand_write_oob_syndrome;
 
-		if (mtd->writesize >= chip->ecc.size)
+		if (mtd->writesize >= chip->ecc.size) {
+			if (!chip->ecc.strength) {
+				pr_warn("Driver must set ecc.strength when using hardware ECC\n");
+				BUG();
+			}
 			break;
+		}
 		pr_warn("%d byte HW ECC not possible on "
 			   "%d byte page size, fallback to SW ECC\n",
 			   chip->ecc.size, mtd->writesize);
@@ -3404,7 +3409,7 @@ int nand_scan_tail(struct mtd_info *mtd)
 			BUG();
 		}
 		chip->ecc.strength =
-			chip->ecc.bytes*8 / fls(8*chip->ecc.size);
+			chip->ecc.bytes * 8 / fls(8 * chip->ecc.size);
 		break;
 
 	case NAND_ECC_NONE: