[PATCH v5 11/11] mtd: gpmi: set the BCH's geometry with the ecc info

[Huang Shijie]

于 2013年05月16日 00:31, Vikram Narayanan 写道:
> Hello Huang,
>
> On 5/15/2013 2:24 PM, Huang Shijie wrote:
>> If the nand chip provides us the ECC info, we can use it firstly.
>> The set_geometry_by_ecc_info() will use the ECC info, and
>> calculate the parameters we need.
>>
>> Rename the old code to lagacy_set_geometry() which will takes effect
>
> Couple of nitpicks.
> Thorough out the code and in comments.
> s/lagacy/legacy/
>
thanks. :)

>> when there is no ECC info from the nand chip or we fails in the ECC 
>> info case.
>>
>> Signed-off-by: Huang Shijie <b32955 at freescale.com>
>> ---
>> drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 128 
>> +++++++++++++++++++++++++++++++-
>> 1 files changed, 127 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c 
>> b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> index 25ecfa1..53180da 100644
>> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> @@ -112,7 +112,128 @@ static inline bool gpmi_check_ecc(struct 
>> gpmi_nand_data *this)
>> return true;
>> }
>>
>> -int common_nfc_set_geometry(struct gpmi_nand_data *this)
>> +/*
>> + * If we can get the ECC information from the nand chip, we do not
>> + * need to calculate them ourselves.
>> + *
>> + * We may have available oob space in this case.
>> + */
>> +static bool set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>> +{
>> + struct bch_geometry *geo = &this->bch_geometry;
>> + struct mtd_info *mtd = &this->mtd;
>> + struct nand_chip *chip = mtd->priv;
>> + struct nand_oobfree *of = gpmi_hw_ecclayout.oobfree;
>> + unsigned int block_mark_bit_offset;
>> +
>> + if (!(chip->ecc_strength > 0 && chip->ecc_step > 0))
>> + return false;
>> +
>> + switch (chip->ecc_step) {
>> + case SZ_512:
>> + geo->gf_len = 13;
>> + break;
>> + case SZ_1K:
>> + geo->gf_len = 14;
>> + break;
>> + default:
>> + dev_err(this->dev,
>> + "unsupported nand chip. ecc bits : %d, ecc size : %d\n",
>> + chip->ecc_strength, chip->ecc_step);
>> + return false;
>> + }
>> + geo->ecc_chunk_size = chip->ecc_step;
>> + geo->ecc_strength = round_up(chip->ecc_strength, 2);
>> + if (!gpmi_check_ecc(this))
>> + return false;
>> +
>> + /* Keep the C >= O */
>> + if (geo->ecc_chunk_size < mtd->oobsize) {
>> + dev_err(this->dev,
>> + "unsupported nand chip. ecc size: %d, oob size : %d\n",
>> + chip->ecc_step, mtd->oobsize);
>> + return false;
>> + }
>> +
>> + /* The default value, see comment in the lagacy_set_geometry(). */
>> + geo->metadata_size = 10;
>
> If this not gonna change, would it be better to keep it as a macro?
>
in actually, it will not changed, the ROM may fixes this value to 10.

I can submit an extra patch to add a macro to fix it. but could we keep 
it as it is in this patch set?



>> +
>> + geo->ecc_chunk_count = mtd->writesize / geo->ecc_chunk_size;
>> +
>> + /*
>> + * Now, the NAND chip with 2K page(data chunk is 512byte) shows below:
>> + *
>> + * | P |
>> + * |<----------------------------------------------------->|
>> + * | |
>> + * | (Block Mark) |
>> + * | P' | | | |
>> + * |<-------------------------------------------->| D | | O' |
>> + * | |<---->| |<--->|
>> + * V V V V V
>> + * +---+----------+-+----------+-+----------+-+----------+-+-----+
>> + * | M | data |E| data |E| data |E| data |E| |
>> + * +---+----------+-+----------+-+----------+-+----------+-+-----+
>> + *
>> + * P : the page size for BCH module.
>> + * E : The ECC strength.
>> + * G : the length of Galois Field.
>> + * N : The chunk count of per page.
>> + * M : the metasize of per page.
>> + * C : the ecc chunk size, aka the "data" above.
>> + * P': the nand chip's page size.
>> + * O : the nand chip's oob size.
>
> I am not sure if my eyes have gone bad. But I couldn't spot the 'O' in 
> the above NAND page diagram.
> I think 's/D/O'.
I do not place the "O" in the diagram.

fix it in later patch version.

thanks
Huang Shijie