Re: [PATCH v6 12/13] mtd: rawnand: brcmnand: Add support for getting ecc setting from strap

[William Zhang <william.zhang@broadcom.com>]

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Hi Miquel,

On 2/23/24 01:18, Miquel Raynal wrote:
> Hi William,
> 
> william.zhang@broadcom.com wrote on Thu, 22 Feb 2024 19:47:57 -0800:
> 
>> BCMBCA broadband SoC based board design does not specify ecc setting in
>> dts but rather use the SoC NAND strap info to obtain the ecc strength
>> and spare area size setting. Add brcm,nand-ecc-use-strap dts propety for
>> this purpose and update driver to support this option. However these two
>> options can not be used at the same time.
>>
>> Signed-off-by: William Zhang <william.zhang@broadcom.com>
>> Reviewed-by: David Regan <dregan@broadcom.com>
>>
> 
> FYI I did not receive patches 7, 8, 9, which makes the series numbering
> very odd.
> 
I was using the get maintainer script mainly and it sends to the linux 
MTD list.  I will add your email directly next time.
>> ---
>>
>> Changes in v6:
>> - Combine the ecc step size and ecc strength into one get function
>> - Treat it as error condition if both brcm,nand-ecc-use-strap and nand
>> ecc dts properties are set
>> - Add intermediate steps to get the sector size bitfield
>>
>> Changes in v5: None
>> Changes in v4:
>> - Update the comments for ecc setting selection
>>
>> Changes in v3: None
>> Changes in v2:
>> - Minor cosmetic fixes
>>
>>   drivers/mtd/nand/raw/brcmnand/brcmnand.c | 83 ++++++++++++++++++++++--
>>   1 file changed, 77 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
>> index ef7d340475be..e8ffc283b365 100644
>> --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
>> +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
>> @@ -1038,6 +1038,22 @@ static inline int brcmnand_sector_1k_shift(struct brcmnand_controller *ctrl)
>>   		return -1;
>>   }
>>   
>> +static int brcmnand_get_sector_size_1k(struct brcmnand_host *host)
>> +{
>> +	struct brcmnand_controller *ctrl = host->ctrl;
>> +	int sector_size_bit = brcmnand_sector_1k_shift(ctrl);
>> +	u16 acc_control_offs = brcmnand_cs_offset(ctrl, host->cs,
>> +						  BRCMNAND_CS_ACC_CONTROL);
>> +	u32 acc_control;
>> +
>> +	if (sector_size_bit < 0)
>> +		return 0;
>> +
>> +	acc_control = nand_readreg(ctrl, acc_control_offs);
>> +
>> +	return (acc_control & BIT(sector_size_bit)) >> sector_size_bit;
> 
> FIELD_PREP, FIELD_GET, *please*.
You probably missed my reply to your comments on the same patch in v5. 
Here is the link for the post in case it lost in your email:
https://lore.kernel.org/lkml/c145b90c-e9f0-4d82-94cc-baf7bfda5954@gmail.com/T/#m1d911d2f119f3bd345c575a81b60bc2bd8c461eb

The mask is not constant here and cause build errors.
> 
>> +}
>> +
>>   static void brcmnand_set_sector_size_1k(struct brcmnand_host *host, int val)
>>   {
>>   	struct brcmnand_controller *ctrl = host->ctrl;
>> @@ -1055,6 +1071,43 @@ static void brcmnand_set_sector_size_1k(struct brcmnand_host *host, int val)
>>   	nand_writereg(ctrl, acc_control_offs, tmp);
>>   }
>>   
>> +static int brcmnand_get_spare_size(struct brcmnand_host *host)
>> +{
>> +	struct brcmnand_controller *ctrl = host->ctrl;
>> +	u16 acc_control_offs = brcmnand_cs_offset(ctrl, host->cs,
>> +						  BRCMNAND_CS_ACC_CONTROL);
>> +	u32 acc = nand_readreg(ctrl, acc_control_offs);
>> +
>> +	return (acc & brcmnand_spare_area_mask(ctrl));
>> +}
>> +
>> +static void brcmnand_get_ecc_settings(struct brcmnand_host *host, struct nand_chip *chip)
>> +{
>> +	struct brcmnand_controller *ctrl = host->ctrl;
>> +	u16 acc_control_offs = brcmnand_cs_offset(ctrl, host->cs,
>> +						  BRCMNAND_CS_ACC_CONTROL);
>> +	int sector_size_1k = brcmnand_get_sector_size_1k(host);
>> +	int spare_area_size, ecc_level;
>> +	u32 acc;
>> +
>> +	spare_area_size = brcmnand_get_spare_size(host);
>> +	acc = nand_readreg(ctrl, acc_control_offs);
>> +	ecc_level = (acc & brcmnand_ecc_level_mask(ctrl)) >> ctrl->ecc_level_shift;
> 
> ditto
> 
>> +	if (sector_size_1k)
>> +		chip->ecc.strength = ecc_level * 2;
>> +	else if (spare_area_size == 16 && ecc_level == 15)
>> +		chip->ecc.strength = 1; /* hamming */
>> +	else
>> +		chip->ecc.strength = ecc_level;
>> +
>> +	if (chip->ecc.size == 0) {
>> +		if (sector_size_1k < 0)
> 
> Should be <= 0 I guess
> 
>> +			chip->ecc.size = 512;
>> +		else
>> +			chip->ecc.size = 512 << sector_size_1k;
> 
> What is this? Are you expecting sector_size_1k to be 0 or 1
> and thus multiply 512 by two?
> 
Explained in the same post above. Sector_size_1k can be negative number 
for error condition where we default to 512 step size. Otherwise 0 for 
512 and 1 for 1K which the above shift takes care of.
> Please just use:
> 			chip->ecc.size = SZ_1K;
> 			
>> +	}
>> +}
>> +
>>   /***********************************************************************
>>    * CS_NAND_SELECT
>>    ***********************************************************************/
>> @@ -2625,19 +2678,37 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
>>   		nanddev_get_memorg(&chip->base);
>>   	struct brcmnand_controller *ctrl = host->ctrl;
>>   	struct brcmnand_cfg *cfg = &host->hwcfg;
>> -	char msg[128];
>> +	struct device_node *np = nand_get_flash_node(chip);
>>   	u32 offs, tmp, oob_sector;
>> +	bool use_strap = false;
>> +	char msg[128];
>>   	int ret;
>>   
>>   	memset(cfg, 0, sizeof(*cfg));
>> +	use_strap = of_property_read_bool(np, "brcm,nand-ecc-use-strap");
>>   
>> -	ret = of_property_read_u32(nand_get_flash_node(chip),
>> -				   "brcm,nand-oob-sector-size",
>> +	/*
>> +	 * Either nand-ecc-xxx or brcm,nand-ecc-use-strap can be set. Error out
>> +	 * if both exist.
>> +	 */
> 
> Thanks for the comment but I think the error string is clear enough.
> 
>> +	if (chip->ecc.strength && use_strap) {
>> +		dev_err(ctrl->dev,
>> +			"nand ecc and strap ecc settings can't be set at the same time\n");
> 
> Can we change to
> "ECC strap and DT ECC configuration properties are mutually exclusive"
> 
Will do.

>> +		return -EINVAL;
>> +	}
>> +
>> +	if (use_strap)
>> +		brcmnand_get_ecc_settings(host, chip);
>> +
>> +	ret = of_property_read_u32(np, "brcm,nand-oob-sector-size",
>>   				   &oob_sector);
>>   	if (ret) {
>> -		/* Use detected size */
>> -		cfg->spare_area_size = mtd->oobsize /
>> -					(mtd->writesize >> FC_SHIFT);
>> +		if (use_strap)
>> +			cfg->spare_area_size = brcmnand_get_spare_size(host);
>> +		else
>> +			/* Use detected size */
>> +			cfg->spare_area_size = mtd->oobsize /
>> +						(mtd->writesize >> FC_SHIFT);
>>   	} else {
>>   		cfg->spare_area_size = oob_sector;
>>   	}
> 
> The rest of the series looks good to me.
> 
> Thanks,
> Miquèl

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