linux-kernel - Re: [PATCH 3/3] mtd: rawnand: qcom: Add support for page scope read

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Message-ID: <20210928161219.GD12183@thinkpad>
Date:   Tue, 28 Sep 2021 21:42:19 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Md Sadre Alam <mdalam@...eaurora.org>
Cc:     miquel.raynal@...tlin.com, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, sricharan@...eaurora.org
Subject: Re: [PATCH 3/3] mtd: rawnand: qcom: Add support for page scope read

On Wed, Sep 15, 2021 at 03:27:31PM +0530, Md Sadre Alam wrote:
> QPIC V2.0 onwards QPIC controller support enhanced read mode
> like page scope read and multi page read.
> 

Define page scope read.

> In QPIC V1, SW is needed to write EXEC_CMD register for each
> Code word and collect any Status related to that CW before
> issueing EXEC_CMD for next CW.
> 
> Page scope command is truly a page mode command where SW is
> required to issue EXEC_CMD only once for a page. Controller
> HW takes care of Codeword specific details and automatically
> returns status associated with each CW to BAM pipe, dedicated
> for status deposition.
> 
> With this command, SW now can issue one read command for a page
> and upon receiving completion interrupt, can process status,
> that have already been deposited in memory through status BAM pipe.
> 
> Signed-off-by: Md Sadre Alam <mdalam@...eaurora.org>
> ---
>  drivers/mtd/nand/raw/qcom_nandc.c | 77 ++++++++++++++++++++++++++++++++++++---
>  1 file changed, 71 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
> index 07448c4..257dec7e 100644
> --- a/drivers/mtd/nand/raw/qcom_nandc.c
> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
> @@ -157,6 +157,10 @@
>  #define	OP_FETCH_ID			0xb
>  #define	OP_RESET_DEVICE			0xd
>  
> +/* Auto status val and mask */
> +#define	AUTO_STS_VAL			0x000B000B

Use non-cap hex.

> +#define PAGE_SCOPE_READ			BIT(23)
> +
>  /* Default Value for NAND_DEV_CMD_VLD */
>  #define NAND_DEV_CMD_VLD_VAL		(READ_START_VLD | WRITE_START_VLD | \
>  					 ERASE_START_VLD | SEQ_READ_START_VLD)
> @@ -336,6 +340,8 @@ struct nandc_regs {
>  
>  	__le32 erased_cw_detect_cfg_clr;
>  	__le32 erased_cw_detect_cfg_set;
> +
> +	__le32 auto_sts_en;
>  };
>  
>  /*
> @@ -421,6 +427,9 @@ struct qcom_nand_controller {
>  
>  	u32 cmd1, vld;
>  	const struct qcom_nandc_props *props;
> +
> +	__le32 *status_buf;
> +	int sts_buf_size;

Add kdoc for these two members.

>  };
>  
>  /*
> @@ -487,6 +496,7 @@ struct qcom_nandc_props {
>  	bool is_bam;
>  	bool is_qpic;
>  	bool qpic_v2;
> +	bool page_scope;
>  	u32 dev_cmd_reg_start;
>  };
>  
> @@ -656,6 +666,8 @@ static __le32 *offset_to_nandc_reg(struct nandc_regs *regs, int offset)
>  		return &regs->cfg1;
>  	case NAND_DEV0_ECC_CFG:
>  		return &regs->ecc_bch_cfg;
> +	case NAND_AUTO_STATUS_EN:
> +		return &regs->auto_sts_en;
>  	case NAND_READ_STATUS:
>  		return &regs->clrreadstatus;
>  	case NAND_DEV_CMD1:
> @@ -756,10 +768,13 @@ static void update_rw_regs(struct qcom_nand_host *host, int num_cw, bool read, i
>  	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
>  
>  	if (read) {
> -		if (host->use_ecc)
> +		if (host->use_ecc) {
>  			cmd = OP_PAGE_READ_WITH_ECC | PAGE_ACC | LAST_PAGE;
> -		else
> +			if (nandc->props->qpic_v2 && nandc->props->page_scope)

Again, why you are checking for both conditions? Using "page_scope" is
sufficient enough.

> +				cmd |= PAGE_SCOPE_READ;
> +		} else {
>  			cmd = OP_PAGE_READ | PAGE_ACC | LAST_PAGE;
> +		}
>  	} else {
>  		cmd = OP_PROGRAM_PAGE | PAGE_ACC | LAST_PAGE;
>  	}

[...]

>  	if (use_ecc) {
> -		read_reg_dma(nandc, NAND_FLASH_STATUS, 2, 0);
> -		read_reg_dma(nandc, NAND_ERASED_CW_DETECT_STATUS, 1,
> -			     NAND_BAM_NEXT_SGL);
> +		if (nandc->props->qpic_v2 && nandc->props->page_scope) {
> +			if (qcom_nandc_is_last_cw(ecc, cw))
> +				write_reg_dma(nandc, NAND_EXEC_CMD, 1,
> +					      NAND_BAM_NEXT_SGL);
> +		} else {
> +			write_reg_dma(nandc, NAND_EXEC_CMD, 1, NAND_BAM_NEXT_SGL);
> +			read_reg_dma(nandc, NAND_FLASH_STATUS, 2, 0);
> +			read_reg_dma(nandc, NAND_ERASED_CW_DETECT_STATUS, 1,
> +				     NAND_BAM_NEXT_SGL);
> +		}

You need to add a comment for this.

Thanks,
Mani