Re: [PATCH] mtd: rawnand: qcom: update last code word register

[mdalam]

On 2021-02-23 22:04, Miquel Raynal wrote:
> Hello,
>
> Md Sadre Alam <mdalam@xxxxxxxxxxxxxx> wrote on Tue, 23 Feb 2021
> 01:34:27 +0530:
>
> > From QPIC version 2.0 onwards new register got added to read last
>
>                                a new
>
> > codeword. This change will add the READ_LOCATION_LAST_CW_n register.
>
>             Add support for this READ_LOCATION_LAST_CW_n register.
>
> > For first three code word READ_LOCATION_n register will be
> > use.For last code word READ_LOCATION_LAST_CW_n register will be
> > use.
>
> "
> In the case of QPIC v2, codewords 0, 1 and 2 will be accessed through
> READ_LOCATION_n, while codeword 3 will be accessed through
> READ_LOCATION_LAST_CW_n.
> "
>
> When I read my own sentence, I feel that there is something wrong.
> If there are only 4 codewords, I guess a QPIC v2 is able to use
> READ_LOCATION_3 or READ_LOCATION_LAST_CW_0 interchangeably. Isn't it?
>
> I guess the point of having these "last_cw_n" registers is to support
> up to 8 codewords, am I wrong? If this the case, the current patch
> completely fails doing that I don't get the point of such change.

This register is only use to read last code word.

I have address all the comments from all the previous sub sequent 
patches and pushed
all patches in only one series.

Please check.

> > Signed-off-by: Md Sadre Alam <mdalam@xxxxxxxxxxxxxx>
> > ---
>
> [...]
>
> >  /* helper to configure address register values */
> > @@ -700,8 +727,9 @@ static void set_address(struct qcom_nand_host 
> > *host, u16 column, int page)
> >   *
> >   * @num_cw:		number of steps for the read/write operation
> >   * @read:		read or write operation
> > + * @cw	:		which code word
> >   */
> > -static void update_rw_regs(struct qcom_nand_host *host, int num_cw, 
> > bool read)
> > +static void update_rw_regs(struct qcom_nand_host *host, int num_cw, 
> > bool read, int cw)
> >  {
> >  	struct nand_chip *chip = &host->chip;
> >  	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
> > @@ -740,7 +768,7 @@ static void update_rw_regs(struct qcom_nand_host 
> > *host, int num_cw, bool read)
> >  	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);
> >
> >  	if (read)
> > -		nandc_set_read_loc(chip, 0, 0, 0, host->use_ecc ?
> > +		nandc_set_read_loc(chip, cw, 0, 0, host->use_ecc ?
> >  				   host->cw_data : host->cw_size, 1);
> >  }
> >
> > @@ -1111,18 +1139,34 @@ static void config_nand_page_read(struct 
> > nand_chip *chip)
> >  		      NAND_ERASED_CW_SET | NAND_BAM_NEXT_SGL);
> >  }
> >
> > +/* helper to check which location register should be use for this
>
>     /*
>      * Check which location...
>
> > + * code word. NAND_READ_LOCATION or NAND_READ_LOCATION_LAST_CW
> > + */
> > +static bool config_loc_last_reg(struct nand_chip *chip, int cw)
> > +{
> > +	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
> > +	struct nand_ecc_ctrl *ecc = &chip->ecc;
> > +
> > +	if (nandc->props->qpic_v2 && qcom_nandc_is_last_cw(ecc, cw))
> > +		return true;
>
> Not sure this is really useful, it's probably better to drop this
> helper and just use...
>
> > +
> > +	return false;
> > +}
> >  /*
> >   * Helper to prepare DMA descriptors for configuring registers
> >   * before reading each codeword in NAND page.
> >   */
> >  static void
> > -config_nand_cw_read(struct nand_chip *chip, bool use_ecc)
> > +config_nand_cw_read(struct nand_chip *chip, bool use_ecc, int cw)
> >  {
> >  	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
> > +	int reg = NAND_READ_LOCATION_0;
> > +
> > +	if (config_loc_last_reg(chip, cw))
>
> ...     if (nandc->props->qpic_v2 && qcom_nandc_is_lastcw()) here.
>
> > +		reg = NAND_READ_LOCATION_LAST_CW_0;
> >
> >  	if (nandc->props->is_bam)
> > -		write_reg_dma(nandc, NAND_READ_LOCATION_0, 4,
> > -			      NAND_BAM_NEXT_SGL);
> > +		write_reg_dma(nandc, reg, 4, NAND_BAM_NEXT_SGL);
> >
> >  	write_reg_dma(nandc, NAND_FLASH_CMD, 1, NAND_BAM_NEXT_SGL);
> >  	write_reg_dma(nandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
> > @@ -1142,12 +1186,12 @@ config_nand_cw_read(struct nand_chip *chip, 
> > bool use_ecc)
>
> Thanks,
> Miquèl