1 files changed, 20 insertions, 0 deletions

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 58b4517ce712..d7a786d5c4a5 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -31,6 +31,7 @@
 #include <linux/types.h>
 #include <linux/jiffies.h>
 #include <linux/async.h>
+#include <linux/dmi.h>
 
 #ifdef CONFIG_ACPI_PROCFS_POWER
 #include <linux/proc_fs.h>
@@ -85,6 +86,10 @@ static const struct acpi_device_id battery_device_ids[] = {
 
 MODULE_DEVICE_TABLE(acpi, battery_device_ids);
 
+/* For buggy DSDTs that report negative 16-bit values for either charging
+ * or discharging current and/or report 0 as 65536 due to bad math.
+ */
+#define QUIRK_SIGNED16_CURRENT 0x0001
 
 struct acpi_battery {
         struct mutex lock;
@@ -112,6 +117,7 @@ struct acpi_battery {
         int state;
         int power_unit;
         u8 alarm_present;
+        long quirks;
 };
 
 #define to_acpi_battery(x) container_of(x, struct acpi_battery, bat);
@@ -390,6 +396,11 @@ static int acpi_battery_get_state(struct acpi_battery *battery)
                                  state_offsets, ARRAY_SIZE(state_offsets));
         battery->update_time = jiffies;
         kfree(buffer.pointer);
+
+        if ((battery->quirks & QUIRK_SIGNED16_CURRENT) &&
+            battery->rate_now != -1)
+                battery->rate_now = abs((s16)battery->rate_now);
+
         return result;
 }
 
@@ -495,6 +506,14 @@ static void sysfs_remove_battery(struct acpi_battery *battery)
 }
 #endif
 
+static void acpi_battery_quirks(struct acpi_battery *battery)
+{
+        battery->quirks = 0;
+        if (dmi_name_in_vendors("Acer") && battery->power_unit) {
+                battery->quirks |= QUIRK_SIGNED16_CURRENT;
+        }
+}
+
 static int acpi_battery_update(struct acpi_battery *battery)
 {
         int result, old_present = acpi_battery_present(battery);
@@ -513,6 +532,7 @@ static int acpi_battery_update(struct acpi_battery *battery)
                 result = acpi_battery_get_info(battery);
                 if (result)
                         return result;
+                acpi_battery_quirks(battery);
                 acpi_battery_init_alarm(battery);
         }
 #ifdef CONFIG_ACPI_SYSFS_POWER