Re: [PATCH 2/3] regulator: max77693: Also manipulate the fast charge current

[Wolfgang Wiedmeyer <wolfgit@wiedmeyer.de>]

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Krzysztof Kozlowski writes:

> On Tue, Sep 27, 2016 at 01:31:09AM +0200, Wolfgang Wiedmeyer wrote:
>> For MAX77693, the fast charge current also needs to be manipulated for
>> proper charging. The fast charge current is only set in the case of
>> the MAX77693 type, as the MAX77843 properly manipulates the fast
>> charge current.
>
> Are you sure it has to be manipulated? Some time I didn't dig into this.
> Now I looked at the datasheet and it says that usually there is no need
> for changing the charge current during the operation. Maxim recommends
> to setting it to a maximum safe value for the battery. The device will
> manage charge current on its own.
>
> However I agree that the charge current should be set... maybe once, to
> a maximum value appropriate for battery. Probably this should be done
> by max77693_charger in max77693_dt_init().

When charging is disabled (e.g. by removing the USB cable) the charge
current is not reset to zero. So if I expose the current by the
CURRENT_NOW property, it incorrectly reports the current that was set
when charging was enabled, although there is no charging going on
anymore. So I felt the need to update the charge current every time the
charger gets enabled or disabled.
Initially, the charge current is set to zero, so I think it needs to be
set at least at the beginning to enable charging.

Thanks,
Wolfgang

> Best regards,
> Krzysztof
>
>
>> The fast charge current is set to the next possible value below the
>> maximum input current.
>
>
>> 
>> Signed-off-by: Wolfgang Wiedmeyer <wolfgit@wiedmeyer.de>
>> ---
>>  drivers/regulator/max77693-regulator.c | 45 +++++++++++++++++++++++++++++++---
>>  1 file changed, 42 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/regulator/max77693-regulator.c b/drivers/regulator/max77693-regulator.c
>> index cfbb951..e2f7584 100644
>> --- a/drivers/regulator/max77693-regulator.c
>> +++ b/drivers/regulator/max77693-regulator.c
>> @@ -54,14 +54,19 @@ struct chg_reg_data {
>>  	unsigned int linear_mask;
>>  	unsigned int uA_step;
>>  	unsigned int min_sel;
>> +
>> +	bool set_fast;
>> +	unsigned int fast_reg;
>> +	unsigned int fast_mask;
>>  };
>>  
>>  /*
>>   * MAX77693 CHARGER regulator - Min : 20mA, Max : 2580mA, step : 20mA
>>   * 0x00, 0x01, 0x2, 0x03	= 60 mA
>>   * 0x04 ~ 0x7E			= (60 + (X - 3) * 20) mA
>> - * Actually for MAX77693 the driver manipulates the maximum input current,
>> - * not the fast charge current (output). This should be fixed.
>> + * Actually for MAX77693 the driver manipulates the maximum input current
>> + * and the fast charge current (output) because the fast charge current
>> + * is not set.
>>   *
>>   * On MAX77843 the calculation formula is the same (except values).
>>   * Fortunately it properly manipulates the fast charge current.
>> @@ -100,6 +105,8 @@ static int max77693_chg_set_current_limit(struct regulator_dev *rdev,
>>  	const struct chg_reg_data *reg_data = rdev_get_drvdata(rdev);
>>  	unsigned int chg_min_uA = rdev->constraints->min_uA;
>>  	int sel = 0;
>> +	unsigned int data;
>> +	int ret;
>>  
>>  	while (chg_min_uA + reg_data->uA_step * sel < min_uA)
>>  		sel++;
>> @@ -110,7 +117,35 @@ static int max77693_chg_set_current_limit(struct regulator_dev *rdev,
>>  	/* the first four codes for charger current are all 60mA */
>>  	sel += reg_data->min_sel;
>>  
>> -	return regmap_write(rdev->regmap, reg_data->linear_reg, sel);
>> +	ret = regmap_write(rdev->regmap, reg_data->linear_reg, sel);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	if (reg_data->set_fast) {
>> +		/* disable fast charge if minimum value */
>> +		if (sel == reg_data->min_sel)
>> +			data = 0;
>> +		else {
>> +			/*
>> +			 * set the fast charge current to the closest value
>> +			 * below the input current
>> +			 */
>> +			ret = regmap_read(rdev->regmap, reg_data->fast_reg,
>> +					  &data);
>> +			if (ret < 0)
>> +				return ret;
>> +
>> +			sel *= reg_data->uA_step / 1000; /* convert to mA */
>> +			data &= ~reg_data->fast_mask;
>> +			data |= sel * 10 / 333; /* 0.1A/3 steps */
>> +		}
>> +
>> +		ret = regmap_write(rdev->regmap, reg_data->fast_reg, data);
>> +		if (ret < 0)
>> +			return ret;
>> +	}
>> +
>> +	return 0;
>>  }
>>  /* end of CHARGER regulator ops */
>>  
>> @@ -197,6 +232,9 @@ static const struct chg_reg_data max77693_chg_reg_data = {
>>  	.linear_mask	= CHG_CNFG_09_CHGIN_ILIM_MASK,
>>  	.uA_step	= 20000,
>>  	.min_sel	= 3,
>> +	.set_fast	= true,
>> +	.fast_reg	= MAX77693_CHG_REG_CHG_CNFG_02,
>> +	.fast_mask	= CHG_CNFG_02_CC_MASK,
>>  };
>>  
>>  #define	max77843_regulator_desc_esafeout(num)	{			\
>> @@ -237,6 +275,7 @@ static const struct chg_reg_data max77843_chg_reg_data = {
>>  	.linear_mask	= MAX77843_CHG_FAST_CHG_CURRENT_MASK,
>>  	.uA_step	= MAX77843_CHG_FAST_CHG_CURRENT_STEP,
>>  	.min_sel	= 2,
>> +	.set_fast	= false,
>>  };
>>  
>>  static int max77693_pmic_probe(struct platform_device *pdev)
>> -- 
>> 2.8.0.rc3
>> 


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