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Subject: Re: [PATCH v2 07/25] mtd: nand: qcom: reorganize nand page read
To: Abhishek Sahu <absahu@codeaurora.org>, dwmw2@infradead.org,
        computersforpeace@gmail.com, boris.brezillon@free-electrons.com,
        marek.vasut@gmail.com, richard@nod.at, cyrille.pitchen@wedev4u.fr,
        robh+dt@kernel.org, mark.rutland@arm.com
Cc: linux-mtd@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        andy.gross@linaro.org, sricharan@codeaurora.org
References: <1500464893-11352-1-git-send-email-absahu@codeaurora.org>
 <1500464893-11352-8-git-send-email-absahu@codeaurora.org>
From: Archit Taneja <architt@codeaurora.org>
Message-ID: <3546bcdb-aa9c-aad2-0de6-d3170626273d@codeaurora.org>
Date: Wed, 2 Aug 2017 11:26:52 +0530
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On 07/19/2017 05:17 PM, Abhishek Sahu wrote:
> Each NAND page consist of multiple codewords. Following is
> sequence for NAND page read according to hardware guide.
> 
> 1. Program Power-up configuration, page row, page column
> address and flash configuration registers.
> 2. Write NAND_FLASH_CMD followed by NANC_EXEC_CMD for each
> codeword.
> 3. Read NAND_FLASH_STATUS for each codeword.
> 
> The step 1 should be done once for each page and step 2,3 should
> be done for each codeword.
> 
> Currently, all the 3 steps are being done for each codeword which
> is wrong. Now this patch reorganizes read page functions to
> configure page specific register once and per codeword specific
> registers for each NAND ECC step.

Looks good to me.

Reviewed-by: Archit Taneja <architt@codeaurora.org>

> 
> Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
> ---
>   drivers/mtd/nand/qcom_nandc.c | 37 +++++++++++++++++++++++++++----------
>   1 file changed, 27 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c
> index 110a26a..27ea594 100644
> --- a/drivers/mtd/nand/qcom_nandc.c
> +++ b/drivers/mtd/nand/qcom_nandc.c
> @@ -605,15 +605,23 @@ static int write_data_dma(struct qcom_nand_controller *nandc, int reg_off,
>   }
>   
>   /*
> - * helper to prepare dma descriptors to configure registers needed for reading a
> - * codeword/step in a page
> + * Helper to prepare DMA descriptors for configuring registers
> + * before reading a NAND page.
>    */
> -static void config_cw_read(struct qcom_nand_controller *nandc)
> +static void config_nand_page_read(struct qcom_nand_controller *nandc)
>   {
> -	write_reg_dma(nandc, NAND_FLASH_CMD, 3);
> +	write_reg_dma(nandc, NAND_ADDR0, 2);
>   	write_reg_dma(nandc, NAND_DEV0_CFG0, 3);
>   	write_reg_dma(nandc, NAND_EBI2_ECC_BUF_CFG, 1);
> +}
>   
> +/*
> + * Helper to prepare DMA descriptors for configuring registers
> + * before reading each codeword in NAND page.
> + */
> +static void config_nand_cw_read(struct qcom_nand_controller *nandc)
> +{
> +	write_reg_dma(nandc, NAND_FLASH_CMD, 1);
>   	write_reg_dma(nandc, NAND_EXEC_CMD, 1);
>   
>   	read_reg_dma(nandc, NAND_FLASH_STATUS, 2);
> @@ -621,9 +629,15 @@ static void config_cw_read(struct qcom_nand_controller *nandc)
>   }
>   
>   /*
> - * helpers to prepare dma descriptors used to configure registers needed for
> - * writing a codeword/step in a page
> + * Helper to prepare dma descriptors to configure registers needed for reading a
> + * single codeword in page
>    */
> +static void config_nand_single_cw_page_read(struct qcom_nand_controller *nandc)
> +{
> +	config_nand_page_read(nandc);
> +	config_nand_cw_read(nandc);
> +}
> +
>   static void config_cw_write_pre(struct qcom_nand_controller *nandc)
>   {
>   	write_reg_dma(nandc, NAND_FLASH_CMD, 3);
> @@ -692,7 +706,7 @@ static int nandc_param(struct qcom_nand_host *host)
>   	nandc->buf_count = 512;
>   	memset(nandc->data_buffer, 0xff, nandc->buf_count);
>   
> -	config_cw_read(nandc);
> +	config_nand_single_cw_page_read(nandc);
>   
>   	read_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer,
>   		      nandc->buf_count);
> @@ -1105,6 +1119,8 @@ static int read_page_ecc(struct qcom_nand_host *host, u8 *data_buf,
>   	struct nand_ecc_ctrl *ecc = &chip->ecc;
>   	int i, ret;
>   
> +	config_nand_page_read(nandc);
> +
>   	/* queue cmd descs for each codeword */
>   	for (i = 0; i < ecc->steps; i++) {
>   		int data_size, oob_size;
> @@ -1118,7 +1134,7 @@ static int read_page_ecc(struct qcom_nand_host *host, u8 *data_buf,
>   			oob_size = host->ecc_bytes_hw + host->spare_bytes;
>   		}
>   
> -		config_cw_read(nandc);
> +		config_nand_cw_read(nandc);
>   
>   		if (data_buf)
>   			read_data_dma(nandc, FLASH_BUF_ACC, data_buf,
> @@ -1178,7 +1194,7 @@ static int copy_last_cw(struct qcom_nand_host *host, int page)
>   	set_address(host, host->cw_size * (ecc->steps - 1), page);
>   	update_rw_regs(host, 1, true);
>   
> -	config_cw_read(nandc);
> +	config_nand_single_cw_page_read(nandc);
>   
>   	read_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer, size);
>   
> @@ -1228,6 +1244,7 @@ static int qcom_nandc_read_page_raw(struct mtd_info *mtd,
>   
>   	host->use_ecc = false;
>   	update_rw_regs(host, ecc->steps, true);
> +	config_nand_page_read(nandc);
>   
>   	for (i = 0; i < ecc->steps; i++) {
>   		int data_size1, data_size2, oob_size1, oob_size2;
> @@ -1246,7 +1263,7 @@ static int qcom_nandc_read_page_raw(struct mtd_info *mtd,
>   			oob_size2 = host->ecc_bytes_hw + host->spare_bytes;
>   		}
>   
> -		config_cw_read(nandc);
> +		config_nand_cw_read(nandc);
>   
>   		read_data_dma(nandc, reg_off, data_buf, data_size1);
>   		reg_off += data_size1;
> 

-- 
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