[PATCH] - change calculating of position page containing BBM

[Piotr Sroka]

Change calculating of position page containing BBM

If none of BBM flags is 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 this 
flag is set if page size is different than 2048 bytes.

This patch changes the nand_bbm_get_next_page function.
It will return 0 if none 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.

Signed-off-by: Piotr Sroka <piotrs@xxxxxxxxxxx>
---
 drivers/mtd/nand/raw/nand_base.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 5c2c30a7dffa..f64e3b6605c6 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/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;
-- 
2.15.0