Hallo Sascha,
On Fri, May 03, 2024 at 09:44:24AM +0200, Sascha Hauer wrote:
> On Tue, Apr 30, 2024 at 11:44:54AM +0200, Uwe Kleine-König wrote:
> > 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);
>
> Could you add the new code to checkbad() instead of inlining it? That
> way it seems easier to adjust the code in case we have to change the way
> how we detect useful data on a page. Rename checkbad() in case the name
> doesn't feel appropriate anymore.
I hesitated to add the check for the chip being pristine to checkbad().
Then maybe read page 0 and check its contents before the check_bad()
loop? Then page 0 will be read twice but checkbad() can stay around and
only do what its name promises.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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