On Wed, May 7, 2025 at 6:32 AM Peter Marheine <pmarheine@xxxxxxxxxxxx> wrote:
>
> The ACPI specification requires that battery rate is always positive,
> but the kernel ABI for POWER_SUPPLY_PROP_CURRENT_NOW
> (Documentation/ABI/testing/sysfs-class-power) specifies that it should
> be negative when a battery is discharging. When reporting CURRENT_NOW,
> massage the value to match the documented ABI.
>
> This only changes the sign of `current_now` and not `power_now` because
> documentation doesn't describe any particular meaning for `power_now` so
> leaving `power_now` unchanged is less likely to confuse userspace
> unnecessarily, whereas becoming consistent with the documented ABI is
> worth potentially confusing clients that read `current_now`.
>
> Signed-off-by: Peter Marheine <pmarheine@xxxxxxxxxxxx>
> ---
> drivers/acpi/battery.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> index 6760330a8a..0ef03142fd 100644
> --- a/drivers/acpi/battery.c
> +++ b/drivers/acpi/battery.c
> @@ -242,6 +242,18 @@ static int acpi_battery_get_property(struct power_supply *psy,
> val->intval = battery->voltage_now * 1000;
> break;
> case POWER_SUPPLY_PROP_CURRENT_NOW:
> + if (battery->rate_now == ACPI_BATTERY_VALUE_UNKNOWN)
> + ret = -ENODEV;
> + else if ((battery->state & ACPI_BATTERY_STATE_DISCHARGING) &&
> + acpi_battery_handle_discharging(battery)
> + == POWER_SUPPLY_STATUS_DISCHARGING)
> + /* ACPI specifies battery rate should always be
> + * positive, but this prop is negative when discharging.
> + */
> + val->intval = battery->rate_now * -1000;
> + else
> + val->intval = battery->rate_now * 1000;
> + break;
> case POWER_SUPPLY_PROP_POWER_NOW:
> if (battery->rate_now == ACPI_BATTERY_VALUE_UNKNOWN)
> ret = -ENODEV;
> --
What about this instead (modulo GMail-induced whitespace breakage):
---
drivers/acpi/battery.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -243,10 +243,22 @@
break;
case POWER_SUPPLY_PROP_CURRENT_NOW:
case POWER_SUPPLY_PROP_POWER_NOW:
- if (battery->rate_now == ACPI_BATTERY_VALUE_UNKNOWN)
+ if (battery->rate_now == ACPI_BATTERY_VALUE_UNKNOWN) {
ret = -ENODEV;
- else
- val->intval = battery->rate_now * 1000;
+ break;
+ }
+
+ val->intval = battery->rate_now * 1000;
+ /*
+ * When discharging, the current should be reported as a
+ * negative number as per the power supply class interface
+ * definition.
+ */
+ if (psp == POWER_SUPPLY_PROP_CURRENT_NOW &&
+ (battery->state & ACPI_BATTERY_STATE_DISCHARGING) &&
+ acpi_battery_handle_discharging(battery) ==
POWER_SUPPLY_STATUS_DISCHARGING)
+ val->intval = -val->intval;
+
break;
case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:
