mtd: rawnand: Change calculating of position page containing BBM

Change calculating of position page containing BBM

If none of BBM flags are set then function nand_bbm_get_next_page
reports EINVAL. It causes that BBM is not read at all during scanning
factory bad blocks. The result is that the BBT table is build without
checking factory BBM at all. For Micron flash memories none of these
flags are set if page size is different than 2048 bytes.

Address this regression by:
- adding NAND_BBM_FIRSTPAGE chip flag without any condition. It solves
  issue only for Micron devices.
- changing the nand_bbm_get_next_page_function. It will return 0
  if no of BBM flag is set and page parameter is 0. After that modification
  way of discovering factory bad blocks will work similar as in kernel
  version 5.1.

Cc: stable@vger.kernel.org
Fixes: f90da7818b (mtd: rawnand: Support bad block markers in first, second or last page)
Signed-off-by: Piotr Sroka <piotrs@cadence.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/nand_base.c

@@ -292,12 +292,16 @@ int nand_bbm_get_next_page(struct nand_chip *chip, int page)
 	struct mtd_info *mtd = nand_to_mtd(chip);
 	int last_page = ((mtd->erasesize - mtd->writesize) >>
 			 chip->page_shift) & chip->pagemask;
+	unsigned int bbm_flags = NAND_BBM_FIRSTPAGE | NAND_BBM_SECONDPAGE
+		| NAND_BBM_LASTPAGE;
 
+	if (page == 0 && !(chip->options & bbm_flags))
+		return 0;
 	if (page == 0 && chip->options & NAND_BBM_FIRSTPAGE)
 		return 0;
-	else if (page <= 1 && chip->options & NAND_BBM_SECONDPAGE)
+	if (page <= 1 && chip->options & NAND_BBM_SECONDPAGE)
 		return 1;
-	else if (page <= last_page && chip->options & NAND_BBM_LASTPAGE)
+	if (page <= last_page && chip->options & NAND_BBM_LASTPAGE)
 		return last_page;
 
 	return -EINVAL;

drivers/mtd/nand/raw/nand_micron.c

@@ -446,8 +446,10 @@ static int micron_nand_init(struct nand_chip *chip)
 	if (ret)
 		goto err_free_manuf_data;
 
+	chip->options |= NAND_BBM_FIRSTPAGE;
+
 	if (mtd->writesize == 2048)
-		chip->options |= NAND_BBM_FIRSTPAGE | NAND_BBM_SECONDPAGE;
+		chip->options |= NAND_BBM_SECONDPAGE;
 
 	ondie = micron_supports_on_die_ecc(chip);