mtd: nand: use read_oob() instead of cmdfunc() for bad block check

The nand_default_block_markbad() and scan_block_fast() use high
level APIs to get access to the BBM.

On the other hand, nand_block_bad (the default implementation of
->block_bad) calls the lower level ->cmdfunc hook.  This prevents
drivers from using ->ecc.read_oob() even if optimized read operation
is implemented.  Besides, some NAND controllers may protect the BBM
with ECC.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/nand_base.c

@@ -354,40 +354,32 @@ static void nand_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len)
  */
 static int nand_block_bad(struct mtd_info *mtd, loff_t ofs)
 {
-	int page, res = 0, i = 0;
+	int page, page_end, res;
 	struct nand_chip *chip = mtd_to_nand(mtd);
-	u16 bad;
+	u8 bad;
 
 	if (chip->bbt_options & NAND_BBT_SCANLASTPAGE)
 		ofs += mtd->erasesize - mtd->writesize;
 
 	page = (int)(ofs >> chip->page_shift) & chip->pagemask;
+	page_end = page + (chip->bbt_options & NAND_BBT_SCAN2NDPAGE ? 2 : 1);
 
-	do {
-		if (chip->options & NAND_BUSWIDTH_16) {
-			chip->cmdfunc(mtd, NAND_CMD_READOOB,
-					chip->badblockpos & 0xFE, page);
-			bad = cpu_to_le16(chip->read_word(mtd));
-			if (chip->badblockpos & 0x1)
-				bad >>= 8;
-			else
-				bad &= 0xFF;
-		} else {
-			chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos,
-					page);
-			bad = chip->read_byte(mtd);
-		}
+	for (; page < page_end; page++) {
+		res = chip->ecc.read_oob(mtd, chip, page);
+		if (res)
+			return res;
+
+		bad = chip->oob_poi[chip->badblockpos];
 
 		if (likely(chip->badblockbits == 8))
 			res = bad != 0xFF;
 		else
 			res = hweight8(bad) < chip->badblockbits;
-		ofs += mtd->writesize;
-		page = (int)(ofs >> chip->page_shift) & chip->pagemask;
-		i++;
-	} while (!res && i < 2 && (chip->bbt_options & NAND_BBT_SCAN2NDPAGE));
-
+		if (res)
 			return res;
+	}
+
+	return 0;
 }
 
 /**