power: supply: Fix logic checking if system is running from battery

The logic used for power_supply_is_system_supplied() counts all power
supplies and assumes that the system is running from AC if there is
either a non-battery power-supply reporting to be online or if no
power-supplies exist at all.

The second rule is for desktop systems, that don't have any
battery/charger devices. These systems will incorrectly report to be
powered from battery once a device scope power-supply is registered
(e.g. a HID device), since these power-supplies increase the counter.

Apart from HID devices, recent dGPUs provide UCSI power supplies on a
desktop systems. The dGPU by default doesn't have anything plugged in so
it's 'offline'. This makes power_supply_is_system_supplied() return 0
with a count of 1 meaning all drivers that use this get a wrong judgement.

To fix this case adjust the logic to also examine the scope of the power
supply. If the power supply is deemed a device power supply, then don't
count it.

Cc: Evan Quan <[email protected]>
Suggested-by: Lijo Lazar <[email protected]>
Signed-off-by: Mario Limonciello <[email protected]>
Signed-off-by: Sebastian Reichel <[email protected]>

Author: superm1

drivers/power/supply/power_supply_core.c

@@ -348,6 +348,10 @@ static int __power_supply_is_system_supplied(struct device *dev, void *data)
 	struct power_supply *psy = dev_get_drvdata(dev);
 	unsigned int *count = data;
 
+	if (!psy->desc->get_property(psy, POWER_SUPPLY_PROP_SCOPE, &ret))
+		if (ret.intval == POWER_SUPPLY_SCOPE_DEVICE)
+			return 0;
+
 	(*count)++;
 	if (psy->desc->type != POWER_SUPPLY_TYPE_BATTERY)
 		if (!psy->desc->get_property(psy, POWER_SUPPLY_PROP_ONLINE,
@@ -366,8 +370,8 @@ int power_supply_is_system_supplied(void)
 				      __power_supply_is_system_supplied);
 
 	/*
-	 * If no power class device was found at all, most probably we are
-	 * running on a desktop system, so assume we are on mains power.
+	 * If no system scope power class device was found at all, most probably we
+	 * are running on a desktop system, so assume we are on mains power.
 	 */
 	if (count == 0)
 		return 1;