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@newsguy.com>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 8718eaf8269f..9f5d339a3610 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: