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

[Abhishek Sahu]

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
> <absahu@xxxxxxxxxxxxxx> 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 <absahu@xxxxxxxxxxxxxx>
> > ---
> > * 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 <miquel.raynal@xxxxxxxxxxx>
>
> Thanks,
> MiquÃl