linux-kernel - Re: [PATCH RFC 06/11] power: supply: max77693: Set charge current limits during init

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Date: Fri, 31 May 2024 11:47:46 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Artur Weber <aweber.kernel@...il.com>,
 Chanwoo Choi <cw00.choi@...sung.com>
Cc: Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Lee Jones <lee@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Alim Akhtar <alim.akhtar@...sung.com>, linux-pm@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org,
 ~postmarketos/upstreaming@...ts.sr.ht, Henrik Grimler <henrik@...mler.se>,
 Wolfgang Wiedmeyer <wolfgit@...dmeyer.de>,
 Denis 'GNUtoo' Carikli <GNUtoo@...erdimension.org>
Subject: Re: [PATCH RFC 06/11] power: supply: max77693: Set charge current
 limits during init

On 30/05/2024 10:55, Artur Weber wrote:
> There are two charger current limit registers:
> 
> - Fast charge current limit (which controls current going from the
>   charger to the battery);
> - CHGIN input current limit (which controls current going into the
>   charger through the cable, and is managed by the CHARGER regulator).
> 
> Add functions for setting both of the values, and set them to a
> safe default value of 500mA at initialization.
> 
> The default value for the fast charge current limit can be modified
> by setting the maxim,fast-charge-current-microamp DT property; the
> CHGIN input current limit will be set up later in the charger detection
> mechanism.
> 
> Signed-off-by: Artur Weber <aweber.kernel@...il.com>
> ---
>  drivers/power/supply/max77693_charger.c | 45 +++++++++++++++++++++++++++++++++
>  1 file changed, 45 insertions(+)
> 
> diff --git a/drivers/power/supply/max77693_charger.c b/drivers/power/supply/max77693_charger.c
> index 894c35b750b3..d59b1524b0a4 100644
> --- a/drivers/power/supply/max77693_charger.c
> +++ b/drivers/power/supply/max77693_charger.c
> @@ -28,6 +28,7 @@ struct max77693_charger {
>  	u32 min_system_volt;
>  	u32 thermal_regulation_temp;
>  	u32 batttery_overcurrent;
> +	u32 fast_charge_current;
>  	u32 charge_input_threshold_volt;
>  };
>  
> @@ -591,6 +592,35 @@ static int max77693_set_batttery_overcurrent(struct max77693_charger *chg,
>  			CHG_CNFG_12_B2SOVRC_MASK, data);
>  }
>  
> +static int max77693_set_input_current_limit(struct max77693_charger *chg,
> +		unsigned int uamp)
> +{
> +	dev_dbg(chg->dev, "CHGIN input current limit: %u\n", uamp);

That's quite useless debug. It duplicates
max77693_set_fast_charge_current(). Just drop entire wrapper.

> +
> +	return regulator_set_current_limit(chg->regu, (int)uamp, (int)uamp);
> +}
> +
> +static int max77693_set_fast_charge_current(struct max77693_charger *chg,
> +		unsigned int uamp)
> +{
> +	unsigned int data;
> +
> +	data = (uamp / 1000) * 10 / 333; /* 0.1A/3 steps */
> +
> +	if (data > CHG_CNFG_02_CC_MASK) {
> +		dev_err(chg->dev, "Wrong value for fast charge current\n");
> +		return -EINVAL;
> +	}
> +
> +	data <<= CHG_CNFG_02_CC_SHIFT;
> +
> +	dev_dbg(chg->dev, "Fast charge current: %u (0x%x)\n", uamp, data);
> +
> +	return regmap_update_bits(chg->max77693->regmap,
> +			MAX77693_CHG_REG_CHG_CNFG_02,
> +			CHG_CNFG_02_CC_MASK, data);

I am surprised that you set current limit via regulator but actual
charging current value here. I think both should go to regulator in such
case.
> 

Best regards,
Krzysztof