by Abhishek Sahu

[permalink] [raw]

Subject: Re: [PATCH v2 09/14] mtd: rawnand: qcom: modify write_oob to remove read codeword part

On 2018-05-22 15:32, Miquel Raynal wrote:
> Hi Abhishek,
>
> Some nitpicking below.
>
> On Thu, 3 May 2018 17:50:36 +0530, Abhishek Sahu
> <[email protected]> wrote:
>
>> QCOM NAND layout protect available OOB data bytes with ECC also so
>
> ^controller
>
>> when ecc->write_oob (qcom_nandc_write_oob) is being called then it
>
> You can just state "->write_oob()"
>
>> can't update just OOB bytes. Currently, it first reads the last
>> codeword which includes old OOB bytes. Then it updates the old OOB
>> bytes with new one and then again writes the codeword back.
>
> ones?
>
>> The reading codeword is unnecessary since all the other bytes
>> should be 0xff only.
>
> since the user is responsible to
> have these bytes cleared to 0xFF.
>
>>
>> This patch removes the read part and updates the oob bytes with
>
> s/oob/OOB/
>
>> all other data bytes as 0xff.
>
> The end of the sentence is not clear for me. Do you mean that padding
> with 0xFF is realized before write?
>
>>
>> Signed-off-by: Abhishek Sahu <[email protected]>
>> ---
>> * Changes from v1:
>>
>> NEW CHANGE
>>
>> drivers/mtd/nand/raw/qcom_nandc.c | 17 +++++------------
>> 1 file changed, 5 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c
>> b/drivers/mtd/nand/raw/qcom_nandc.c
>> index 61d0e7d..f85d8ab 100644
>> --- a/drivers/mtd/nand/raw/qcom_nandc.c
>> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
>> @@ -2067,10 +2067,9 @@ static int qcom_nandc_write_page_raw(struct
>> mtd_info *mtd,
>> * implements ecc->write_oob()
>> *
>> * the NAND controller cannot write only data or only oob within a
>> codeword,
>
> s/oob/OOB/
>
> Remove the trailing ','
>
>> - * since ecc is calculated for the combined codeword. we first copy
>> the
>> - * entire contents for the last codeword(data + oob), replace the old
>> oob
>> - * with the new one in chip->oob_poi, and then write the entire
>> codeword.
>> - * this read-copy-write operation results in a slight performance
>> loss.
>> + * since ecc is calculated for the combined codeword. So make all the
>> data
>
> s/ecc/ECC/
>
>> + * bytes as 0xff and update the oob from chip->oob_poi, and then
>> write
>> + * the entire codeword again.
>
> What about "Pad the data area with OxFF before writing."?
>
>> */
>> static int qcom_nandc_write_oob(struct mtd_info *mtd, struct
>> nand_chip *chip,
>> int page)
>> @@ -2082,20 +2081,14 @@ static int qcom_nandc_write_oob(struct
>> mtd_info *mtd, struct nand_chip *chip,
>> int data_size, oob_size;
>> int ret;
>>
>> - host->use_ecc = true;
>> -
>> - clear_bam_transaction(nandc);
>> - ret = copy_last_cw(host, page);
>> - if (ret)
>> - return ret;
>> -
>> - clear_read_regs(nandc);
>> clear_bam_transaction(nandc);
>>
>> /* calculate the data and oob size for the last codeword/step */
>> data_size = ecc->size - ((ecc->steps - 1) << 2);
>> oob_size = mtd->oobavail;
>> + host->use_ecc = true;
>
> You don't need to move this line here, do you?
>
>>
>> + memset(nandc->data_buffer, 0xff, host->cw_data);
>> /* override new oob content to last codeword */
>> mtd_ooblayout_get_databytes(mtd, nandc->data_buffer + data_size,
>> oob,
>> 0, mtd->oobavail);
>
>
> Once fixed, you can add my:

Thanks Miquel.
I will fix all these and update the patch.

Regards,
Abhishek

>
> Acked-by: Miquel Raynal <[email protected]>
>
> Thanks,
> Miquèl