[PATCH] acpi/battery: fix wrong value of capacity_now reported by few battery types when fully charged

Josef Gajdusek
2014-06-12T14:45:15Z

It seems that some batteries (noticed on DELL JYPJ136) assume
capacity_now = design_capacity when fully charged. This causes
reported capacity to suddenly jump to >full_charge_capacity (and that
means capacity reported to userspace is >100% and incorrect)
values after 99%. This patch attempts to detect this bug and trims
capacity_now properly.

---
diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index e48fc98..3338dd5 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -532,6 +532,14 @@ static int acpi_battery_get_state(struct acpi_battery *battery)
" invalid.\n");
}

+ /* When fully charged, some batteries wrongly report
+ * capacity_now = design_capacity instead of = full_charge_capacity
+ */
+ if (battery->capacity_now == battery->design_capacity &&
+ battery->full_charge_capacity != ACPI_BATTERY_VALUE_UNKNOWN)
+ battery->capacity_now = battery->full_charge_capacity;
+
+
if (test_bit(ACPI_BATTERY_QUIRK_PERCENTAGE_CAPACITY, &battery->flags)
&& battery->capacity_now >= 0 && battery->capacity_now <= 100)
battery->capacity_now = (battery->capacity_now *