Re: [PATCH] power: supply: bd71828: add input current limit property

Matti Vaittinen
2026-04-07T05:34:17Z

On 02/04/2026 00:17, Andreas Kemnade wrote:
> Add input current property to be able to work around issues created by
> automatic input limiting and have some control.
> Disabling the automatic management is another step.
>
> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> ---
> drivers/power/supply/bd71828-power.c | 62 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 62 insertions(+)
>
> diff --git a/drivers/power/supply/bd71828-power.c b/drivers/power/supply/bd71828-power.c
> index 0e00acb589937..5e78faa0a4aaf 100644
> --- a/drivers/power/supply/bd71828-power.c
> +++ b/drivers/power/supply/bd71828-power.c
> @@ -24,6 +24,7 @@
> #define BD7182x_MASK_CONF_PON BIT(0)
> #define BD71815_MASK_CONF_XSTB BIT(1)
> #define BD7182x_MASK_BAT_STAT 0x3f
> +#define BD7182x_MASK_ILIM 0x3f
> #define BD7182x_MASK_DCIN_STAT 0x07
>
> #define BD7182x_MASK_WDT_AUTO 0x40
> @@ -48,9 +49,11 @@ struct pwr_regs {
> unsigned int vbat_avg;
> unsigned int ibat;
> unsigned int ibat_avg;
> + unsigned int ilim_stat;
> unsigned int btemp_vth;
> unsigned int chg_state;
> unsigned int bat_temp;
> + unsigned int dcin_set;
> unsigned int dcin_stat;
> unsigned int dcin_online_mask;
> unsigned int dcin_collapse_limit;
> @@ -66,9 +69,11 @@ static const struct pwr_regs pwr_regs_bd71828 = {
> .vbat_avg = BD71828_REG_VBAT_U,
> .ibat = BD71828_REG_IBAT_U,
> .ibat_avg = BD71828_REG_IBAT_AVG_U,
> + .ilim_stat = BD71828_REG_ILIM_STAT,
> .btemp_vth = BD71828_REG_VM_BTMP_U,
> .chg_state = BD71828_REG_CHG_STATE,
> .bat_temp = BD71828_REG_BAT_TEMP,
> + .dcin_set = BD71828_REG_DCIN_SET,

Hi Andreas / Sebastian,

Sorry for belated review (although, I don't think this did float on the
list quite THAT long...)

I believe this is the ILIM_STAT register in the data sheet, at address
0x6d, right? (The bit field is named as: LIM_DCIN_STAT[5:0]). If so,
then I have a follow-up question in the setter...

> .dcin_stat = BD71828_REG_DCIN_STAT,
> .dcin_online_mask = BD7182x_MASK_DCIN_DET,
> .dcin_collapse_limit = BD71828_REG_DCIN_CLPS,
> @@ -441,6 +446,7 @@ static int bd71828_charger_get_property(struct power_supply *psy,
> struct bd71828_power *pwr = dev_get_drvdata(psy->dev.parent);
> u32 vot;
> u16 tmp;
> + int t;
> int online;
> int ret;
>
> @@ -459,6 +465,20 @@ static int bd71828_charger_get_property(struct power_supply *psy,
> vot = tmp;
> /* 5 milli volt steps */
> val->intval = 5000 * vot;
> + break;
> + case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> + if (!pwr->regs->ilim_stat)
> + return -ENODATA;
> +
> + ret = regmap_read(pwr->regmap, pwr->regs->ilim_stat, &t);
> + if (ret)
> + return ret;
> +
> + t++;
> + val->intval = (t & BD7182x_MASK_ILIM) * 50000;
> + if (val->intval > 2000000)
> + val->intval = 2000000;

I would have preferred using the linear-ranges here.

> +
> break;
> default:
> return -EINVAL;
> @@ -467,6 +487,45 @@ static int bd71828_charger_get_property(struct power_supply *psy,
> return 0;
> }
>
> +static int bd71828_charger_set_property(struct power_supply *psy,
> + enum power_supply_property psp,
> + const union power_supply_propval *val)
> +{
> + struct bd71828_power *pwr = dev_get_drvdata(psy->dev.parent);
> +
> + switch (psp) {
> + case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> + if (val->intval > 2000000)
> + return -EINVAL;
> +
> + if (val->intval < 50000)
> + return -EINVAL;
> +

I would have preferred using the linear ranges here as well. That'd help
if we support this in the other variants.

> + if (!pwr->regs->dcin_set)
> + return -EINVAL;
> +
> + return regmap_update_bits(pwr->regmap, pwr->regs->dcin_set,
> + BD7182x_MASK_ILIM,
> + val->intval / 50000 - 1);

The "burning question" I have is - how well this has been verified? I
ask because the data-sheet version which I read (rev 0p17, DS2 draft)
marks this register as a read-only. I know my data-sheet, targeting the
design-sample 2 of bd71828 (not bd71879) is ancient. It may be this is
an error in the data-sheet but I had to ask anyways...

> + break;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int bd71828_charger_property_is_writeable(struct power_supply *psy,
> + enum power_supply_property psp)
> +{
> + struct bd71828_power *pwr = dev_get_drvdata(psy->dev.parent);
> +
> + switch (psp) {
> + case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> + return !!(pwr->regs->dcin_set);
> + default:
> + return false;
> + }
> +}
> +
> static int bd71828_battery_get_property(struct power_supply *psy,
> enum power_supply_property psp,
> union power_supply_propval *val)
> @@ -571,6 +630,7 @@ static int bd71828_battery_property_is_writeable(struct power_supply *psy,
>
> /** @brief ac properties */
> static const enum power_supply_property bd71828_charger_props[] = {
> + POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
> POWER_SUPPLY_PROP_ONLINE,
> POWER_SUPPLY_PROP_VOLTAGE_NOW,
> };
> @@ -600,6 +660,8 @@ static const struct power_supply_desc bd71828_ac_desc = {
> .properties = bd71828_charger_props,
> .num_properties = ARRAY_SIZE(bd71828_charger_props),
> .get_property = bd71828_charger_get_property,
> + .set_property = bd71828_charger_set_property,
> + .property_is_writeable = bd71828_charger_property_is_writeable,
> };
>
> static const struct power_supply_desc bd71828_bat_desc = {
>
> ---
> base-commit: 7aaa8047eafd0bd628065b15757d9b48c5f9c07d
> change-id: 20260401-bd-inp-limit-3acb51e15e9c
>
> Best regards,
> --
> Andreas Kemnade <andreas@kemnade.info>