1 files changed, 45 insertions, 10 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index bb5ed059114a..f0e6eb534161 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -294,7 +294,7 @@ static int acpi_video_device_lcd_get_level_current(
                         unsigned long long *level);
 static int acpi_video_get_next_level(struct acpi_video_device *device,
                                      u32 level_current, u32 event);
-static void acpi_video_switch_brightness(struct acpi_video_device *device,
+static int acpi_video_switch_brightness(struct acpi_video_device *device,
                                          int event);
 static int acpi_video_device_get_state(struct acpi_video_device *device,
                             unsigned long long *state);
@@ -308,7 +308,9 @@ static int acpi_video_get_brightness(struct backlight_device *bd)
         int i;
         struct acpi_video_device *vd =
                 (struct acpi_video_device *)bl_get_data(bd);
-        acpi_video_device_lcd_get_level_current(vd, &cur_level);
+
+        if (acpi_video_device_lcd_get_level_current(vd, &cur_level))
+                return -EINVAL;
         for (i = 2; i < vd->brightness->count; i++) {
                 if (vd->brightness->levels[i] == cur_level)
                         /* The first two entries are special - see page 575
@@ -373,7 +375,8 @@ static int video_get_cur_state(struct thermal_cooling_device *cdev, char *buf)
         unsigned long long level;
         int state;
 
-        acpi_video_device_lcd_get_level_current(video, &level);
+        if (acpi_video_device_lcd_get_level_current(video, &level))
+                return -EINVAL;
         for (state = 2; state < video->brightness->count; state++)
                 if (level == video->brightness->levels[state])
                         return sprintf(buf, "%d\n",
@@ -502,11 +505,29 @@ static int
 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
                                         unsigned long long *level)
 {
-        if (device->cap._BQC)
-                return acpi_evaluate_integer(device->dev->handle, "_BQC", NULL,
-                                             level);
+        acpi_status status = AE_OK;
+
+        if (device->cap._BQC) {
+                status = acpi_evaluate_integer(device->dev->handle, "_BQC",
+                                                NULL, level);
+                if (ACPI_SUCCESS(status)) {
+                        device->brightness->curr = *level;
+                        return 0;
+                } else {
+                        /* Fixme:
+                         * should we return an error or ignore this failure?
+                         * dev->brightness->curr is a cached value which stores
+                         * the correct current backlight level in most cases.
+                         * ACPI video backlight still works w/ buggy _BQC.
+                         * http://bugzilla.kernel.org/show_bug.cgi?id=12233
+                         */
+                        ACPI_WARNING((AE_INFO, "Evaluating _BQC failed"));
+                        device->cap._BQC = 0;
+                }
+        }
+
         *level = device->brightness->curr;
-        return AE_OK;
+        return 0;
 }
 
 static int
@@ -1749,15 +1770,29 @@ acpi_video_get_next_level(struct acpi_video_device *device,
         }
 }
 
-static void
+static int
 acpi_video_switch_brightness(struct acpi_video_device *device, int event)
 {
         unsigned long long level_current, level_next;
+        int result = -EINVAL;
+
         if (!device->brightness)
-                return;
-        acpi_video_device_lcd_get_level_current(device, &level_current);
+                goto out;
+
+        result = acpi_video_device_lcd_get_level_current(device,
+                                                         &level_current);
+        if (result)
+                goto out;
+
         level_next = acpi_video_get_next_level(device, level_current, event);
+
         acpi_video_device_lcd_set_level(device, level_next);
+
+out:
+        if (result)
+                printk(KERN_ERR PREFIX "Failed to switch the brightness\n");
+
+        return result;
 }
 
 static int