Re: [PATCH v11 6/7] power: supply: Add driver for ASUS Transformer battery

[Dmitry Torokhov]

Hi Svyatoslav,

On Tue, Oct 13, 2026 at 08:35:02PM +0300, Svyatoslav Ryhel wrote:
> +static int asus_ec_battery_get_property(struct power_supply *psy,
> +					enum power_supply_property psp,
> +					union power_supply_propval *val)
> +{
> +	struct asus_ec_battery_data *priv = power_supply_get_drvdata(psy);
> +	int ret;
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_PRESENT:
> +		val->intval = 1;
> +		break;
> +
> +	default:
> +		ret = asus_ec_battery_get_value(priv, psp);
> +		if (ret < 0)
> +			return ret;
> +
> +		val->intval = (s16)ret;
> +
> +		switch (psp) {
...
> +		case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
> +		case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW:
> +			val->intval *= 60;
> +			break;

asus_ec_battery_get_value() returns a u16 (via get_unaligned_le16()), and
unconditionally casting it with (s16)ret sign-extends unsigned 16-bit
properties >= 0x8000 into negative values.

In particular, when the battery is not discharging or not charging,
TIME_TO_EMPTY_NOW / TIME_TO_FULL_NOW report 0xffff, which (s16)ret turns
into -1 and then -60 seconds instead of an unsigned value (or -ENODATA).
Should only signed properties (like POWER_SUPPLY_PROP_CURRENT_NOW) be cast
to s16?

Thanks.

-- 
Dmitry