ACPI video: ignore buggy _BQC

_BQC doesn't return a value listed in _BCL method.
http://bugzilla.kernel.org/show_bug.cgi?id=13511

ingore the buggy _BQC method in this case

Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Signed-off-by: Scott Howard <showard314@gmail.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index a0cd0c7ee9e2..2020907921cc 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -603,6 +603,7 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
                                         unsigned long long *level)
 {
         acpi_status status = AE_OK;
+        int i;
 
         if (device->cap._BQC || device->cap._BCQ) {
                 char *buf = device->cap._BQC ? "_BQC" : "_BCQ";
@@ -618,8 +619,15 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
 
                         }
                         *level += bqc_offset_aml_bug_workaround;
-                        device->brightness->curr = *level;
-                        return 0;
+                        for (i = 2; i < device->brightness->count; i++)
+                                if (device->brightness->levels[i] == *level) {
+                                        device->brightness->curr = *level;
+                                        return 0;
+                        }
+                        /* BQC returned an invalid level. Stop using it.  */
+                        ACPI_WARNING((AE_INFO, "%s returned an invalid level",
+                                                buf));
+                        device->cap._BQC = device->cap._BCQ = 0;
                 } else {
                         /* Fixme:
                          * should we return an error or ignore this failure?