nand: reinstate lazy bad block scanning

Commit ff94bc40af
("mtd, ubi, ubifs: resync with Linux-3.14")
accidentally reverted part of the commit
13f0fd94e3
("NAND: Scan bad blocks lazily.").

Reinstate the change as by commit
fb49454b1b
("nand: reinstate lazy bad block scanning")

Signed-off-by: Rostislav Lisovy <lisovy@merica.cz>
Acked-by: Heiko Schocher <hs@denx.de>

drivers/mtd/nand/nand_base.c

@@ -634,6 +634,11 @@ static int nand_block_checkbad(struct mtd_info *mtd, loff_t ofs, int getchip,
 {
 	struct nand_chip *chip = mtd->priv;
 
+	if (!(chip->options & NAND_BBT_SCANNED)) {
+		chip->scan_bbt(mtd);
+		chip->options |= NAND_BBT_SCANNED;
+	}
+
 	if (!chip->bbt)
 		return chip->block_bad(mtd, ofs, getchip);
 
@@ -4322,10 +4327,9 @@ int nand_scan_tail(struct mtd_info *mtd)
 
 	/* Check, if we should skip the bad block table scan */
 	if (chip->options & NAND_SKIP_BBTSCAN)
-		return 0;
+		chip->options |= NAND_BBT_SCANNED;
 
-	/* Build bad block table */
-	return chip->scan_bbt(mtd);
+	return 0;
 }
 EXPORT_SYMBOL(nand_scan_tail);