[PATCH v2] power: supply: axp20x_battery: properly report current when discharging

[PATCH v2] power: supply: axp20x_battery: properly report current when discharging

[Evgeny Boger]

As stated in [1], negative current values are used for discharging
batteries.

AXP PMICs internally have two different ADC channels for shunt current
measurement: one used during charging and one during discharging.
The values reported by these ADCs are unsigned.
While the driver properly selects ADC channel to get the data from,
it doesn't apply negative sign when reporting discharging current.

[1] Documentation/ABI/testing/sysfs-class-power

Signed-off-by: Evgeny Boger <boger@wirenboard.com>
---
Changes from v1:
 * fix formatting, no other changes

 drivers/power/supply/axp20x_battery.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/power/supply/axp20x_battery.c b/drivers/power/supply/axp20x_battery.c
index 5d197141f476..9106077c0dbb 100644
--- a/drivers/power/supply/axp20x_battery.c
+++ b/drivers/power/supply/axp20x_battery.c
@@ -186,7 +186,6 @@ static int axp20x_battery_get_prop(struct power_supply *psy,
 				   union power_supply_propval *val)
 {
 	struct axp20x_batt_ps *axp20x_batt = power_supply_get_drvdata(psy);
-	struct iio_channel *chan;
 	int ret = 0, reg, val1;
 
 	switch (psp) {
@@ -266,12 +265,12 @@ static int axp20x_battery_get_prop(struct power_supply *psy,
 		if (ret)
 			return ret;
 
-		if (reg & AXP20X_PWR_STATUS_BAT_CHARGING)
-			chan = axp20x_batt->batt_chrg_i;
-		else
-			chan = axp20x_batt->batt_dischrg_i;
-
-		ret = iio_read_channel_processed(chan, &val->intval);
+		if (reg & AXP20X_PWR_STATUS_BAT_CHARGING) {
+			ret = iio_read_channel_processed(axp20x_batt->batt_chrg_i, &val->intval);
+		} else {
+			ret = iio_read_channel_processed(axp20x_batt->batt_dischrg_i, &val1);
+			val->intval = -val1;
+		}
 		if (ret)
 			return ret;
 
-- 
2.25.1

Re: [PATCH v2] power: supply: axp20x_battery: properly report current when discharging

[Chen-Yu Tsai]

On Wed, Jan 12, 2022 at 4:47 PM Evgeny Boger <boger@wirenboard.com> wrote:
>
> As stated in [1], negative current values are used for discharging
> batteries.
>
> AXP PMICs internally have two different ADC channels for shunt current
> measurement: one used during charging and one during discharging.
> The values reported by these ADCs are unsigned.
> While the driver properly selects ADC channel to get the data from,
> it doesn't apply negative sign when reporting discharging current.
>
> [1] Documentation/ABI/testing/sysfs-class-power
>
> Signed-off-by: Evgeny Boger <boger@wirenboard.com>

Acked-by: Chen-Yu Tsai <wens@csie.org>