Automatically creating a BBT is the right thing to do if the NAND is
factory new. However when migrating from a barebox older than commit
v2020.03.0~28^2~1 ("mtd: nand-imx: Create BBT automatically when
necessary") on a used machine, this automatism is really bad because it
most likely marks the blocks containing the barebox image (and possibly
more) as bad. On such a system the vendor BBMs are gone, but it was
operated without that information before, so continuing to do so is a
sane option.
Add a light check for the NAND to be really pristine: If any block looks
like containing a barebox image or a UBI refuse to create a BBT.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
---
drivers/mtd/nand/raw/mxc_nand.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/mtd/nand/raw/mxc_nand.c b/drivers/mtd/nand/raw/mxc_nand.c
index faea1c95f95e..f8517df823e5 100644
--- a/drivers/mtd/nand/raw/mxc_nand.c
+++ b/drivers/mtd/nand/raw/mxc_nand.c
@@ -1575,6 +1575,23 @@ static int checkbad(struct mtd_info *mtd, loff_t ofs)
return ret;
}
+ /*
+ * Automatically adding a BBT based on factory BBTs is only
+ * sensible if the NAND is pristine. Abort if the first page
+ * looks like a bootloader or UBI block.
+ */
+ if (is_barebox_arm_head(buf)) {
+ dev_err(mtd->dev.parent,
+ "Flash seems to contain a barebox image, refusing to create BBT\n");
+ return -EINVAL;
+ }
+
+ if (!memcmp(buf, "UBI#", 4)) {
+ dev_err(mtd->dev.parent,
+ "Flash seems to contain a UBI, refusing to create BBT\n");
+ return -EINVAL;
+ }
+
if (buf[2000] != 0xff)
/* block considered bad */
return 1;
--
2.43.0
