On Thu, 27 Oct 2016 14:14:01 -0500
Zach Brown <zach.br...@ni.com> wrote:
> From: Jeff Westfahl <jeff.westf...@ni.com>
>
> Implement the new mtd function 'max_bad_blocks'. Use the ONFI parameter
> page to find the maximum bad blocks to reserve for an MTD, taking into
> account how many LUNs the MTD spans.
>
> Signed-off-by: Jeff Westfahl <jeff.westf...@ni.com>
> Signed-off-by: Zach Brown <zach.br...@ni.com>
> ---
> drivers/mtd/nand/nand_base.c | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index e5718e5..ac08224 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -3226,6 +3226,39 @@ static int nand_block_markbad(struct mtd_info *mtd,
> loff_t ofs)
> }
>
> /**
> + * nand_max_bad_blocks - [MTD Interface] Max number of bad blocks for an mtd
> + * @mtd: MTD device structure
> + * @ofs: offset relative to mtd start
> + * @len: length of mtd
> + */
> +static int nand_max_bad_blocks(struct mtd_info *mtd, loff_t ofs, size_t len)
> +{
> + struct nand_chip *chip = mtd_to_nand(mtd);
> + uint32_t part_start_block;
> + uint32_t part_end_block;
> + uint32_t part_start_lun;
> + uint32_t part_end_lun;
> +
> + /* ONFI is used to determine the maximum bad block count. */
> + if (!chip->onfi_version)
> + return -ENOTSUPP;
> +
> + /* Get the start and end of the partition in erase blocks. */
> + part_start_block = mtd_div_by_eb(ofs, mtd);
> + part_end_block = mtd_div_by_eb(len, mtd) + part_start_block - 1;
> +
> + /* Get the start and end LUNs of the partition. */
> + part_start_lun = part_start_block / chip->onfi_params.blocks_per_lun;
> + part_end_lun = part_end_block / chip->onfi_params.blocks_per_lun;
> +
> + /* Look up the bad blocks per unit and multiply by the number of units
> + * that the partition spans.
> + */
> + return chip->onfi_params.bb_per_lun *
> + (part_end_lun - part_start_lun + 1);
Well, it's a good start, but I'd like to have something that works even
for non-ONFI chips. How about adding a field in nand_chip and filling
this field when the ONFI param page is retrieved/parsed. This way we
can easily extend the implementation for full-id entries in the
nand_ids table or for JEDEC compliant chips (assuming the JEDEC
standard provides such information).
> +}
> +
> +/**
> * nand_onfi_set_features- [REPLACEABLE] set features for ONFI nand
> * @mtd: MTD device structure
> * @chip: nand chip info structure
> @@ -4743,6 +4776,7 @@ int nand_scan_tail(struct mtd_info *mtd)
> mtd->_block_isreserved = nand_block_isreserved;
> mtd->_block_isbad = nand_block_isbad;
> mtd->_block_markbad = nand_block_markbad;
> + mtd->_max_bad_blocks = nand_max_bad_blocks;
> mtd->writebufsize = mtd->writesize;
>
> /*
