ACPI / battery: Use design-cap for capacity calculations if full-cap is not available

The ThunderSoft TS178 tablet's _BIX implementation reports design_capacity
but not full_charge_capacity.

Before this commit this would cause us to return -ENODEV for the capacity
attribute, which userspace does not like. Specifically upower does this:

        if (sysfs_file_exists (native_path, "capacity")) {
                percentage = sysfs_get_double (native_path, "capacity");

Where the sysfs_get_double() helper returns 0 when we return -ENODEV,
so the battery always reads 0% if we return -ENODEV.

This commit fixes this by using the design-capacity instead of the
full-charge-capacity when the full-charge-capacity is not available.

Fixes: b41901a2cf06 ("ACPI / battery: Do not export energy_full[_design] on devices without full_charge_capacity")
Cc: 4.19+ <stable@vger.kernel.org> # 4.19+
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 0862d38e51fa2affe608b7cfc141568085553aaa..85a6c3c3631c091b2516dc685aae96a30d5e9683 100644 (file)
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -217,7 +217,7 @@ static int acpi_battery_get_property(struct power_supply *psy,
                                     enum power_supply_property psp,
                                     union power_supply_propval *val)
 {
-       int ret = 0;
+       int full_capacity = ACPI_BATTERY_VALUE_UNKNOWN, ret = 0;
        struct acpi_battery *battery = to_acpi_battery(psy);
 
        if (acpi_battery_present(battery)) {
@@ -286,12 +286,17 @@ static int acpi_battery_get_property(struct power_supply *psy,
                        val->intval = battery->capacity_now * 1000;
                break;
        case POWER_SUPPLY_PROP_CAPACITY:
+               if (ACPI_BATTERY_CAPACITY_VALID(battery->full_charge_capacity))
+                       full_capacity = battery->full_charge_capacity;
+               else if (ACPI_BATTERY_CAPACITY_VALID(battery->design_capacity))
+                       full_capacity = battery->design_capacity;
+
                if (battery->capacity_now == ACPI_BATTERY_VALUE_UNKNOWN ||
-                   !ACPI_BATTERY_CAPACITY_VALID(battery->full_charge_capacity))
+                   full_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
                        ret = -ENODEV;
                else
                        val->intval = battery->capacity_now * 100/
-                                       battery->full_charge_capacity;
+                                       full_capacity;
                break;
        case POWER_SUPPLY_PROP_CAPACITY_LEVEL:
                if (battery->state & ACPI_BATTERY_STATE_CRITICAL)