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Date:   Tue, 16 Feb 2021 00:49:05 +0530
From:   mdalam@codeaurora.org
To:     Miquel Raynal <miquel.raynal@bootlin.com>
Cc:     richard@nod.at, vigneshr@ti.com, boris.brezillon@collabora.com,
        mani@kernel.org, krzk@kernel.org, linux-mtd@lists.infradead.org,
        linux-kernel@vger.kernel.org, sricharan@codeaurora.org
Subject: Re: [PATCH] mtd: rawnand: qcom: update last code word register
In-Reply-To: <20210215094055.1c3847f8@xps13>
References: <1613337451-8002-1-git-send-email-mdalam@codeaurora.org>
 <20210215094055.1c3847f8@xps13>
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On 2021-02-15 14:10, Miquel Raynal wrote:
> Hello,
> 
> Md Sadre Alam <mdalam@codeaurora.org> wrote on Mon, 15 Feb 2021
> 02:47:31 +0530:
> 
>> From QPIC version 2.0 onwards new register got added to
>> read last codeword. This change will add the 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.
>> 
>> Signed-off-by: Md Sadre Alam <mdalam@codeaurora.org>
>> ---
>> [V5]
>>  * Added helper function to update location register value.
> 
> 
> Please don't forget the "v5" in the message object.
> 
>>  /*
>> @@ -1094,11 +1141,16 @@ static void config_nand_page_read(struct 
>> qcom_nand_controller *nandc)
>>   * before reading each codeword in NAND page.
>>   */
>>  static void
>> -config_nand_cw_read(struct qcom_nand_controller *nandc, bool use_ecc)
>> +config_nand_cw_read(struct qcom_nand_controller *nandc, bool use_ecc, 
>> bool last_cw)
>>  {
>> -	if (nandc->props->is_bam)
>> -		write_reg_dma(nandc, NAND_READ_LOCATION_0, 4,
>> -			      NAND_BAM_NEXT_SGL);
>> +	if (nandc->props->is_bam) {
>> +		if (nandc->props->qpic_v2 && last_cw)
>> +			write_reg_dma(nandc, NAND_READ_LOCATION_LAST_CW_0, 4,
>> +				      NAND_BAM_NEXT_SGL);
>> +		else
>> +			write_reg_dma(nandc, NAND_READ_LOCATION_0, 4,
>> +				      NAND_BAM_NEXT_SGL);
> 
> I guess write_reg_dma should be updated as well.

   Updated in V6 patch , please check.
> 
> 
> [...]
> 
>> 
>> -	config_nand_cw_read(nandc, false);
>> +	config_nand_cw_read(nandc, false, cw == ecc->steps - 1 ? true : 
>> false);
>> 
>>  	read_data_dma(nandc, reg_off, data_buf, data_size1, 0);
>>  	reg_off += data_size1;
>> @@ -1873,18 +1938,31 @@ static int read_page_ecc(struct qcom_nand_host 
>> *host, u8 *data_buf,
>> 
>>  		if (nandc->props->is_bam) {
>>  			if (data_buf && oob_buf) {
>> -				nandc_set_read_loc(nandc, 0, 0, data_size, 0);
>> -				nandc_set_read_loc(nandc, 1, data_size,
>> -						   oob_size, 1);
>> +				if (nandc->props->qpic_v2 && i == (ecc->steps - 1)) {
> 
> I would like the helper to handle this condition. I would prefer to
> avoid yet an extra indentation level.

   Updated in V6 patch , please check.
> 
>> +					nandc_set_read_loc(chip, i, 0, 0, data_size, 0);
>> +					nandc_set_read_loc(chip, i, 1, data_size,
>> +							   oob_size, 1);
>> +				} else {
>> +					nandc_set_read_loc(chip, i, 0, 0, data_size, 0);
>> +					nandc_set_read_loc(chip, i, 1, data_size,
>> +							   oob_size, 1);
>> +				}
>>  			} else if (data_buf) {
>> -				nandc_set_read_loc(nandc, 0, 0, data_size, 1);
>> +				if (nandc->props->qpic_v2 && i == (ecc->steps - 1))
>> +					nandc_set_read_loc(chip, i, 0, 0, data_size, 1);
>> +				else
>> +					nandc_set_read_loc(chip, i, 0, 0, data_size, 1);
>>  			} else {
>> -				nandc_set_read_loc(nandc, 0, data_size,
>> -						   oob_size, 1);
>> +				if (nandc->props->qpic_v2 && i == (ecc->steps - 1))
>> +					nandc_set_read_loc(chip, i, 0, data_size,
>> +							   oob_size, 1);
>> +				else
>> +					nandc_set_read_loc(chip, i, 0, data_size,
>> +							   oob_size, 1);
>>  			}
>>  		}
>> 
>> -		config_nand_cw_read(nandc, true);
>> +		config_nand_cw_read(nandc, true, i == ecc->steps - 1 ? true : 
>> false);
> 
> 	i == (ecc->steps - 1)
> 
> is already a boolean, you don't need
> 
> 	"? true : false"
> 

    Updated in V6 patch.

>> 
>>  		if (data_buf)
>>  			read_data_dma(nandc, FLASH_BUF_ACC, data_buf,
>> @@ -1946,7 +2024,7 @@ 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_nand_single_cw_page_read(nandc, host->use_ecc);
>> +	config_nand_single_cw_page_read(nandc, host->use_ecc, true);
> 
> Maybe it's best to just forward the codeword and let the code that
> needs to know if it is the last one or not do the comparison.
> 

   Updated in V6 patch, please check.
>> 
>>  	read_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer, size, 0);
>> 
> 
> Thanks,
> Miquèl