1 files changed, 67 insertions, 25 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index cd4fb7543a90..810cca90ca7f 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -538,6 +538,41 @@ 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"),
+                },
+        },
+        {}
+};
+
 static int
 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
                                         unsigned long long *level)
@@ -557,6 +592,7 @@ 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 +806,12 @@ 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 +845,19 @@ 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 +865,19 @@ 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 +2326,15 @@ 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 __exit acpi_video_exit(void)
 {
 
         acpi_bus_unregister_driver(&acpi_video_bus);
@@ -2302,6 +2343,7 @@ static void __exit acpi_video_exit(void)
 
         return;
 }
+EXPORT_SYMBOL(acpi_video_exit);
 
 module_init(acpi_video_init);
 module_exit(acpi_video_exit);