Re: [PATCH v4 2/2] mtd: nand: write BBM to OOB even with flash-based BBT

["Bityutskiy, Artem" <artem.bityutskiy@intel.com>]

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On Fri, 2012-01-20 at 20:38 -0800, Brian Norris wrote:
> Currently, the flash-based BBT implementation writes bad block data only
> to its flash-based table and not to the OOB marker area. Then, as new bad
> blocks are marked over time, the OOB markers become out of date and the
> flash-based table becomes the only source of current bad block
> information.

I think the comment could be corrected: OOB markers become incomplete,
not out-of-date?


>   * This is the default implementation, which can be overridden by a hardware
> - * specific driver.
> + * specific driver. We try operations in the following order, according to our
> + * bbt_options (NAND_BBT_NO_OOB_BBM and NAND_BBT_USE_FLASH):
> + *  (1) erase the affected block, to allow OOB marker to be written cleanly
> + *  (2) update in-memory BBT
> + *  (3) write bad block marker to OOB area of affected block
> + *  (4) update flash-based BBT
> + * Note that we retain the first error encountered in (3) or (4), finish the
> + * procedures, and dump the error in the end.
>  */
>  static int nand_default_block_markbad(struct mtd_info *mtd, loff_t ofs)
>  {
>  	struct nand_chip *chip = mtd->priv;
>  	uint8_t buf[2] = { 0, 0 };
> -	int block, ret, i = 0;
> +	int block, res, ret = 0, i = 0;
> +	int write_oob = !(chip->bbt_options & NAND_BBT_NO_OOB_BBM);
>  
> -	if (!(chip->bbt_options & NAND_BBT_USE_FLASH)) {
> +	BUG_ON((chip->bbt_options & NAND_BBT_NO_OOB_BBM) &&
> +			!(chip->bbt_options & NAND_BBT_USE_FLASH));

If get the chip options wrong then this will be noticed only in the
field when a block gets bad? Probably we better put all the validation
of chip options to the NAND scan function so that incorrect combinations
are noticed immediately. Probably with a comment why.

Otherwise looks OK and I guess we could merge it.

-- 
Best Regards,
Artem Bityutskiy

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