ACPI / battery: Deal with design or full capacity being reported as -1

Commit b41901a2cf06 ("ACPI / battery: Do not export energy_full[_design]
on devices without full_charge_capacity") added support for some (broken)
devices which always report 0 for both design- and full_charge-capacity.

This assumes that if the capacity is not being reported it is 0. The
ThunderSoft TS178 tablet's _BIX implementation falsifies this assumption.
It reports ACPI_BATTERY_VALUE_UNKNOWN (-1) as full_charge_capacity, which
we treat as a valid value which causes several problems.

This commit fixes this by adding a new ACPI_BATTERY_CAPACITY_VALID() helper
which checks that the value is not 0 and not -1; and using this whenever we
need to test if either design_capacity or full_charge_capacity is valid.

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 8f0e0c8d8c3d902586736b66e5ff7544ffc78582..0862d38e51fa2affe608b7cfc141568085553aaa 100644 (file)
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -38,6 +38,8 @@
 #define PREFIX "ACPI: "
 
 #define ACPI_BATTERY_VALUE_UNKNOWN 0xFFFFFFFF
+#define ACPI_BATTERY_CAPACITY_VALID(capacity) \
+       ((capacity) != 0 && (capacity) != ACPI_BATTERY_VALUE_UNKNOWN)
 
 #define ACPI_BATTERY_DEVICE_NAME       "Battery"
 
@@ -192,7 +194,8 @@ static int acpi_battery_is_charged(struct acpi_battery *battery)
 
 static bool acpi_battery_is_degraded(struct acpi_battery *battery)
 {
-       return battery->full_charge_capacity && battery->design_capacity &&
+       return ACPI_BATTERY_CAPACITY_VALID(battery->full_charge_capacity) &&
+               ACPI_BATTERY_CAPACITY_VALID(battery->design_capacity) &&
                battery->full_charge_capacity < battery->design_capacity;
 }
 
@@ -263,14 +266,14 @@ static int acpi_battery_get_property(struct power_supply *psy,
                break;
        case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
        case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:
-               if (battery->design_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
+               if (!ACPI_BATTERY_CAPACITY_VALID(battery->design_capacity))
                        ret = -ENODEV;
                else
                        val->intval = battery->design_capacity * 1000;
                break;
        case POWER_SUPPLY_PROP_CHARGE_FULL:
        case POWER_SUPPLY_PROP_ENERGY_FULL:
-               if (battery->full_charge_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
+               if (!ACPI_BATTERY_CAPACITY_VALID(battery->full_charge_capacity))
                        ret = -ENODEV;
                else
                        val->intval = battery->full_charge_capacity * 1000;
@@ -283,11 +286,12 @@ static int acpi_battery_get_property(struct power_supply *psy,
                        val->intval = battery->capacity_now * 1000;
                break;
        case POWER_SUPPLY_PROP_CAPACITY:
-               if (battery->capacity_now && battery->full_charge_capacity)
+               if (battery->capacity_now == ACPI_BATTERY_VALUE_UNKNOWN ||
+                   !ACPI_BATTERY_CAPACITY_VALID(battery->full_charge_capacity))
+                       ret = -ENODEV;
+               else
                        val->intval = battery->capacity_now * 100/
                                        battery->full_charge_capacity;
-               else
-                       val->intval = 0;
                break;
        case POWER_SUPPLY_PROP_CAPACITY_LEVEL:
                if (battery->state & ACPI_BATTERY_STATE_CRITICAL)
@@ -799,7 +803,8 @@ static int sysfs_add_battery(struct acpi_battery *battery)
                battery->bat_desc.properties = charge_battery_props;
                battery->bat_desc.num_properties =
                        ARRAY_SIZE(charge_battery_props);
-       } else if (battery->full_charge_capacity == 0) {
+       } else if (!ACPI_BATTERY_CAPACITY_VALID(
+                                       battery->full_charge_capacity)) {
                battery->bat_desc.properties =
                        energy_battery_full_cap_broken_props;
                battery->bat_desc.num_properties =