On Fri, Apr 29, 2016 at 09:16:31PM +0200, Boris Brezillon wrote: > On Fri, 29 Apr 2016 12:34:18 -0500 > Kyle Roeschley <kyle.roesch...@ni.com> wrote: > > > Hi Boris, > > > > On Wed, Mar 30, 2016 at 03:16:23PM +0200, Boris Brezillon wrote: > > > +Peter, who's currently reworking the NAND BBT code. > > > > > > On Wed, 30 Mar 2016 15:13:51 +0200 > > > Boris Brezillon <boris.brezil...@free-electrons.com> wrote: > > > > > > > Hi Kyle, > > > > > > > > On Fri, 25 Mar 2016 17:31:16 -0500 > > > > Kyle Roeschley <kyle.roesch...@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.westf...@ni.com>. > > > > > > > > > > Signed-off-by: Kyle Roeschley <kyle.roesch...@ni.com> > > > > > Suggested-by: Jeff Westfahl <jeff.westf...@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? > > > > > > > > Having looked into this more, no. Since v2, we called block_markbad in > > write_bbt incorrectly and caused the chip to report that it was write > > protected. Fixing that makes this unnecessary. > > > > > > > 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). > > > > > > > > Will do. > > > > > > > > > > > > /* > > > > > * 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 :-/) > > > > > > > > So is your suggestion here just to swap the order of block_markbad and > > bbt_mark_entry? > > No, my suggestion was to move this->block_markbad() call after > scan_write_bbt(), but this leads to another problem: if the BBT content > is still valid after the erasure and you move this->block_markbad(), > you might have a power-cut in the middle and the BBT detection code > will pick the first valid one BBT (i.e. the one you were about to mark > as bad). > Again, this is all hypothetical, and anyway, the current BBT > implementation is not so robust, so maybe we shouldn't care and rely on > full bad block scan in this case (too bad for controllers that did not > take care of keeping valid bad block markers :-/).
Sounds like a plan, I'll work on this. -- Kyle Roeschley Software Engineer National Instruments
