1 files changed, 27 insertions, 24 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 8961e613e09..d7ff61c0d57 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -770,10 +770,12 @@ acpi_video_init_brightness(struct acpi_video_device *device)
 	 * In this case, the first two elements in _BCL packages
 	 * are also supported brightness levels that OS should take care of.
 	 */
-	for (i = 2; i < count; i++)
-		if (br->levels[i] == br->levels[0] ||
-		    br->levels[i] == br->levels[1])
+	for (i = 2; i < count; i++) {
+		if (br->levels[i] == br->levels[0])
 			level_ac_battery++;
+		if (br->levels[i] == br->levels[1])
+			level_ac_battery++;
+	}
 
 	if (level_ac_battery < 2) {
 		level_ac_battery = 2 - level_ac_battery;
@@ -807,12 +809,19 @@ acpi_video_init_brightness(struct acpi_video_device *device)
 	br->flags._BCM_use_index = br->flags._BCL_use_index;
 
 	/* _BQC uses INDEX while _BCL uses VALUE in some laptops */
-	br->curr = max_level;
+	br->curr = level_old = max_level;
+
+	if (!device->cap._BQC)
+		goto set_level;
+
 	result = acpi_video_device_lcd_get_level_current(device, &level_old);
 	if (result)
 		goto out_free_levels;
 
-	result = acpi_video_device_lcd_set_level(device, br->curr);
+	/*
+	 * Set the level to maximum and check if _BQC uses indexed value
+	 */
+	result = acpi_video_device_lcd_set_level(device, max_level);
 	if (result)
 		goto out_free_levels;
 
@@ -820,25 +829,19 @@ acpi_video_init_brightness(struct acpi_video_device *device)
 	if (result)
 		goto out_free_levels;
 
-	if ((level != level_old) && !br->flags._BCM_use_index) {
-		/* Note:
-		 * This piece of code does not work correctly if the current
-		 * brightness levels is 0.
-		 * But I guess boxes that boot with such a dark screen are rare
-		 * and no more code is needed to cover this specifial case.
-		 */
-
-		if (level_ac_battery != 2) {
-			/*
-			 * For now, we don't support the _BCL like this:
-			 * 16, 15, 0, 1, 2, 3, ..., 14, 15, 16
-			 * because we may mess up the index returned by _BQC.
-			 * Plus: we have not got a box like this.
-			 */
-			ACPI_ERROR((AE_INFO, "_BCL not supported\n"));
-		}
-		br->flags._BQC_use_index = 1;
-	}
+	br->flags._BQC_use_index = (level == max_level ? 0 : 1);
+
+	if (!br->flags._BQC_use_index)
+		goto set_level;
+
+	if (br->flags._BCL_reversed)
+		level_old = (br->count - 1) - level_old;
+	level_old = br->levels[level_old];
+
+set_level:
+	result = acpi_video_device_lcd_set_level(device, level_old);
+	if (result)
+		goto out_free_levels;
 
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 			  "found %d brightness levels\n", count - 2));