[U-Boot-Users] skipping bad blocks when erasing nand

[Ladislav Michl <ladis@linux-mips.org>]

Dear Wolfgang,

On Fri, Jul 14, 2006 at 01:19:23PM +0200, Wolfgang Denk wrote:
> In message <44B76ABA.3000607@fsforth.de> you wrote:
> > 
> > / # mtd_debug erase /dev/mtd/2 0x22f00000 0x3000000
> > nand_erase: attempt to erase a bad block at page 0x0004bf40
> > MEMERASE: Input/output error
> 
> That's the behaviour I would expect to see from looking at the code.
> 
> And what you will see in U-Boot, too - same code, same behaviour.

Indeed, but MTD code in U-Boot is invoked different way (that's my bad
and I apologize for late reply). Most Linux users are probably using
mtd-utils to deal with erasing NAND. flash_erase will issue MEMERASE
ioctl directly and that will fail on attempt to erase bad block. However
flash_eraseall will first ask for bad block using MEMGETBADBLOCK ioctl
and eventually skip it, printing info message "Skipping bad block at 0x%08x"
Average U-Boot user probably wants flash_eraseall behaviour...

> > I think, bad blocks should not prevent U-Boot from erasing a partition,
> > which is needed to write an OS there, which needs to be booted.
> 
> I tend to agree here, which was the reason that I said I was  willing
> to  accept  the patch, but that at least the printf() shoould be kept
> so that the user gets the warning.

So, it seems the only unanswered question is implementation. You can
either accept second version of proposed patch or ask for different
implementation which will be similar to flash_eraseall (ie. bad block
checking done outside MTD code, so it can remain unmodified). Not being
U-Boot maintainer I trade off decision :-)

Best regards,
	ladis