1 files changed, 83 insertions, 25 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index cd4fb7543a9..1bdfb37377e 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -538,6 +538,57 @@ acpi_video_device_lcd_set_level(struct acpi_video_device *device, int level)
 	return -EINVAL;
 }
 
+/*
+ * For some buggy _BQC methods, we need to add a constant value to
+ * the _BQC return value to get the actual current brightness level
+ */
+
+static int bqc_offset_aml_bug_workaround;
+static int __init video_set_bqc_offset(const struct dmi_system_id *d)
+{
+	bqc_offset_aml_bug_workaround = 9;
+	return 0;
+}
+
+static struct dmi_system_id video_dmi_table[] __initdata = {
+	/*
+	 * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
+	 */
+	{
+	 .callback = video_set_bqc_offset,
+	 .ident = "Acer Aspire 5720",
+	 .matches = {
+		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
+		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5720"),
+		},
+	},
+	{
+	 .callback = video_set_bqc_offset,
+	 .ident = "Acer Aspire 5710Z",
+	 .matches = {
+		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
+		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5710Z"),
+		},
+	},
+	{
+	 .callback = video_set_bqc_offset,
+	 .ident = "eMachines E510",
+	 .matches = {
+		DMI_MATCH(DMI_BOARD_VENDOR, "EMACHINES"),
+		DMI_MATCH(DMI_PRODUCT_NAME, "eMachines E510"),
+		},
+	},
+	{
+	 .callback = video_set_bqc_offset,
+	 .ident = "Acer Aspire 5315",
+	 .matches = {
+		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
+		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5315"),
+		},
+	},
+	{}
+};
+
 static int
 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
 					unsigned long long *level)
@@ -557,6 +608,7 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
 				*level = device->brightness->levels[*level + 2];
 
 			}
+			*level += bqc_offset_aml_bug_workaround;
 			device->brightness->curr = *level;
 			return 0;
 		} else {
@@ -770,10 +822,12 @@ 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 +861,19 @@ 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 +881,19 @@ 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));
@@ -2287,13 +2342,15 @@ EXPORT_SYMBOL(acpi_video_register);
 
 static int __init acpi_video_init(void)
 {
+	dmi_check_system(video_dmi_table);
+
 	if (intel_opregion_present())
 		return 0;
 
 	return acpi_video_register();
 }
 
-static void __exit acpi_video_exit(void)
+void acpi_video_exit(void)
 {
 
 	acpi_bus_unregister_driver(&acpi_video_bus);
@@ -2302,6 +2359,7 @@ static void __exit acpi_video_exit(void)
 
 	return;
 }
+EXPORT_SYMBOL(acpi_video_exit);
 
 module_init(acpi_video_init);
 module_exit(acpi_video_exit);