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 the first 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 | 58 ++++++++++++++++++---------------
1 file changed, 31 insertions(+), 27 deletions(-)
diff --git a/drivers/mtd/nand/raw/mxc_nand.c b/drivers/mtd/nand/raw/mxc_nand.c
index a72275480144..fd5ae447a198 100644
--- a/drivers/mtd/nand/raw/mxc_nand.c
+++ b/drivers/mtd/nand/raw/mxc_nand.c
@@ -1555,30 +1555,6 @@ static const struct nand_controller_ops mxcnd_controller_ops = {
* From this point on we can forget about the BBMs and rely completely
* on the flash BBT.
*/
-static int checkbad(struct nand_chip *chip, loff_t ofs)
-{
- struct mtd_info *mtd = nand_to_mtd(chip);
- int ret;
- uint8_t buf[mtd->writesize + mtd->oobsize];
- struct mtd_oob_ops ops;
-
- ops.mode = MTD_OPS_RAW;
- ops.ooboffs = 0;
- ops.datbuf = buf;
- ops.len = mtd->writesize;
- ops.oobbuf = buf + mtd->writesize;
- ops.ooblen = mtd->oobsize;
-
- ret = mtd_read_oob(mtd, ofs, &ops);
- if (ret < 0)
- return ret;
-
- if (buf[2000] != 0xff)
- return 1;
-
- return 0;
-}
-
static int imxnd_create_bbt(struct nand_chip *chip)
{
struct mtd_info *mtd = nand_to_mtd(chip);
@@ -1598,12 +1574,40 @@ static int imxnd_create_bbt(struct nand_chip *chip)
for (i = 0; i < numblocks; ++i) {
loff_t ofs = i << chip->bbt_erase_shift;
+ uint8_t buf[mtd->writesize + mtd->oobsize];
+ struct mtd_oob_ops ops = {
+ .mode = MTD_OPS_RAW,
+ .ooboffs = 0,
+ .datbuf = buf,
+ .len = mtd->writesize,
+ .oobbuf = buf + mtd->writesize,
+ .ooblen = mtd->oobsize,
+ };
- ret = checkbad(chip, ofs);
- if (ret < 0)
+ ret = mtd_read_oob(mtd, ofs, &ops);
+ if (ret < 0) {
+ dev_err(mtd->dev.parent, "Failed to read page at 0x%08x\n", (unsigned int)ofs);
goto out;
+ }
- if (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 (ofs == 0 && is_barebox_arm_head(buf)) {
+ dev_err(mtd->dev.parent, "Flash seems to contain a barebox image, refusing\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (ofs == 0 && !memcmp(buf, "UBI#", 4)) {
+ dev_err(mtd->dev.parent, "Flash seems to contain a UBI, refusing\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (buf[2000] != 0xff) {
bbt[i >> 2] |= 0x03 << (2 * (i & 0x3));
dev_info(mtd->dev.parent, "Bad eraseblock %d at 0x%08x\n",
i, (unsigned int)ofs);
--
2.43.0
