lkml.org 
[lkml]   [2016]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3] mtd: nand_bbt: scan for next free bbt block if writing bbt fails
    Hi Kyle,

    On Fri, 25 Mar 2016 17:31:16 -0500
    Kyle Roeschley <kyle.roeschley@ni.com> wrote:

    > If erasing or writing the BBT fails, we should mark the current BBT
    > block as bad and use the BBT descriptor to scan for the next available
    > unused block in the BBT. We should only return a failure if there isn't
    > any space left.
    >
    > Based on original code implemented by Jeff Westfahl
    > <jeff.westfahl@ni.com>.
    >
    > Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
    > Suggested-by: Jeff Westfahl <jeff.westfahl@ni.com>
    > ---
    > This v3 is in response to comments from Brian Norris and Bean Ho on 8/26/15:
    > http://lists.infradead.org/pipermail/linux-mtd/2015-August/061411.html
    >
    > v3: Don't overload mtd->priv
    > Keep nand_erase_nand from erroring on protected BBT blocks
    >
    > v2: Mark OOB area in each block as well as BBT
    > Avoid marking read-only, bad address, or known bad blocks as bad
    > ---
    > drivers/mtd/nand/nand_base.c | 4 ++--
    > drivers/mtd/nand/nand_bbt.c | 37 +++++++++++++++++++++++++++++++++++--
    > 2 files changed, 37 insertions(+), 4 deletions(-)
    >
    > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
    > index b6facac..9ad8a86 100644
    > --- a/drivers/mtd/nand/nand_base.c
    > +++ b/drivers/mtd/nand/nand_base.c
    > @@ -2916,8 +2916,8 @@ int nand_erase_nand(struct mtd_info *mtd, struct erase_info *instr,
    > /* Select the NAND device */
    > chip->select_chip(mtd, chipnr);
    >
    > - /* Check, if it is write protected */
    > - if (nand_check_wp(mtd)) {
    > + /* Check if it is write protected, unless we're erasing BBT */
    > + if (nand_check_wp(mtd) && !allowbbt) {

    Hm, will this really work. Can a write-protected device accept erase
    commands?

    > pr_debug("%s: device is write protected!\n",
    > __func__);
    > instr->state = MTD_ERASE_FAILED;
    > diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
    > index 2fbb523..01526e5 100644
    > --- a/drivers/mtd/nand/nand_bbt.c
    > +++ b/drivers/mtd/nand/nand_bbt.c
    > @@ -662,6 +662,7 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
    > page = td->pages[chip];
    > goto write;
    > }
    > + next:

    Please put this label at the beginning of the line and fix all the other
    issues reported by checkpatch (I know we already have a 'write' label
    which does not follow this rule, but let's try to avoid adding new
    ones).

    >
    > /*
    > * Automatic placement of the bad block table. Search direction
    > @@ -787,14 +788,46 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
    > einfo.addr = to;
    > einfo.len = 1 << this->bbt_erase_shift;
    > res = nand_erase_nand(mtd, &einfo, 1);
    > - if (res < 0)
    > + if (res == -EIO) {
    > + /* This block is bad. Mark it as such and see if
    > + * there's another block available in the BBT area. */
    > + int block = page >>
    > + (this->bbt_erase_shift - this->page_shift);
    > + pr_info("nand_bbt: failed to erase block %d when writing BBT\n",
    > + block);
    > + bbt_mark_entry(this, block, BBT_BLOCK_WORN);
    > +
    > + res = this->block_markbad(mtd, block);

    Not sure we should mark the block bad until we managed to write a new
    BBT. ITOH, if we do so and the new BBT write is interrupted, it
    will trigger a full BBM scan, which should be harmless on most
    platforms (except those overwriting BBM with real data :-/)

    > + if (res)
    > + pr_warn("nand_bbt: error %d while marking block %d bad\n",
    > + res, block);
    > + td->pages[chip] = -1;
    > + goto next;
    > + } else if (res < 0) {
    > goto outerr;
    > + }
    >
    > res = scan_write_bbt(mtd, to, len, buf,
    > td->options & NAND_BBT_NO_OOB ? NULL :
    > &buf[len]);
    > - if (res < 0)
    > + if (res == -EIO) {
    > + /* This block is bad. Mark it as such and see if
    > + * there's another block available in the BBT area. */
    > + int block = page >>
    > + (this->bbt_erase_shift - this->page_shift);
    > + pr_info("nand_bbt: failed to write block %d when writing BBT\n",
    > + block);
    > + bbt_mark_entry(this, block, BBT_BLOCK_WORN);
    > +
    > + res = this->block_markbad(mtd, block);
    > + if (res)
    > + pr_warn("nand_bbt: error %d while marking block %d bad\n",
    > + res, block);
    > + td->pages[chip] = -1;
    > + goto next;
    > + } else if (res < 0) {
    > goto outerr;
    > + }
    >
    > pr_info("Bad block table written to 0x%012llx, version 0x%02X\n",
    > (unsigned long long)to, td->version[chip]);

    Bean, Brian, can you comment on this new version. I haven't followed
    the previous iterations, and would like to have your feedback before
    taking a decision.

    Thanks,

    Boris


    --
    Boris Brezillon, Free Electrons
    Embedded Linux and Kernel engineering
    http://free-electrons.com

    \
     
     \ /
      Last update: 2016-03-30 15:41    [W:4.591 / U:0.352 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site