ACPI / battery: If _BIX fails, retry with _BIF

The Lenovo Yoga 300 laptop's firmware advertises that it provides the _BIX
the method to retrieve battery information. Unfortunately (some versions
of?) the implementation return with an error.

[   21.712228] ACPI Exception: AE_AML_PACKAGE_LIMIT, Index (0x000000010) is beyond end of object (length 0xD) (20160422/exoparg2-427)
[   21.712244] ACPI Error: Method parse/execution failed [\_SB.PCI0.LPCB.H_EC.BAT1._BIX] (Node ffff95f8ff0b20f0), AE_AML_PACKAGE_LIMIT (20160422/psparse-542)

The _BIF method does succeed and returns convincing data. We detect _BIX
failing and automatically retry with _BIF.

Signed-off-by: Dave Lambley <linux@davel.me.uk>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 93ecae55fe6a02452a8e7974c0d290f46ccae836..05fe9ebfb9b5d8acd5625b3bb16e34f2c03b6a4b 100644 (file)
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -430,39 +430,24 @@ static int acpi_battery_get_status(struct acpi_battery *battery)
        return 0;
 }
 
-static int acpi_battery_get_info(struct acpi_battery *battery)
+
+static int extract_battery_info(const int use_bix,
+                        struct acpi_battery *battery,
+                        const struct acpi_buffer *buffer)
 {
        int result = -EFAULT;
-       acpi_status status = 0;
-       char *name = test_bit(ACPI_BATTERY_XINFO_PRESENT, &battery->flags) ?
-                       "_BIX" : "_BIF";
-
-       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 
-       if (!acpi_battery_present(battery))
-               return 0;
-       mutex_lock(&battery->lock);
-       status = acpi_evaluate_object(battery->device->handle, name,
-                                               NULL, &buffer);
-       mutex_unlock(&battery->lock);
-
-       if (ACPI_FAILURE(status)) {
-               ACPI_EXCEPTION((AE_INFO, status, "Evaluating %s", name));
-               return -ENODEV;
-       }
-
-       if (battery_bix_broken_package)
-               result = extract_package(battery, buffer.pointer,
+       if (use_bix && battery_bix_broken_package)
+               result = extract_package(battery, buffer->pointer,
                                extended_info_offsets + 1,
                                ARRAY_SIZE(extended_info_offsets) - 1);
-       else if (test_bit(ACPI_BATTERY_XINFO_PRESENT, &battery->flags))
-               result = extract_package(battery, buffer.pointer,
+       else if (use_bix)
+               result = extract_package(battery, buffer->pointer,
                                extended_info_offsets,
                                ARRAY_SIZE(extended_info_offsets));
        else
-               result = extract_package(battery, buffer.pointer,
+               result = extract_package(battery, buffer->pointer,
                                info_offsets, ARRAY_SIZE(info_offsets));
-       kfree(buffer.pointer);
        if (test_bit(ACPI_BATTERY_QUIRK_PERCENTAGE_CAPACITY, &battery->flags))
                battery->full_charge_capacity = battery->design_capacity;
        if (test_bit(ACPI_BATTERY_QUIRK_THINKPAD_MAH, &battery->flags) &&
@@ -483,6 +468,45 @@ static int acpi_battery_get_info(struct acpi_battery *battery)
        return result;
 }
 
+static int acpi_battery_get_info(struct acpi_battery *battery)
+{
+       const int xinfo = test_bit(ACPI_BATTERY_XINFO_PRESENT, &battery->flags);
+       int use_bix;
+       int result = -ENODEV;
+
+       if (!acpi_battery_present(battery))
+               return 0;
+
+
+       for (use_bix = xinfo ? 1 : 0; use_bix >= 0; use_bix--) {
+               struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+               acpi_status status = AE_ERROR;
+
+               mutex_lock(&battery->lock);
+               status = acpi_evaluate_object(battery->device->handle,
+                                             use_bix ? "_BIX":"_BIF",
+                                             NULL, &buffer);
+               mutex_unlock(&battery->lock);
+
+               if (ACPI_FAILURE(status)) {
+                       ACPI_EXCEPTION((AE_INFO, status, "Evaluating %s",
+                                       use_bix ? "_BIX":"_BIF"));
+               } else {
+                       result = extract_battery_info(use_bix,
+                                                     battery,
+                                                     &buffer);
+
+                       kfree(buffer.pointer);
+                       break;
+               }
+       }
+
+       if (!result && !use_bix && xinfo)
+               pr_warn(FW_BUG "The _BIX method is broken, using _BIF.\n");
+
+       return result;
+}
+
 static int acpi_battery_get_state(struct acpi_battery *battery)
 {
        int result = 0;