ACPI: Ignore _BQC object when registering backlight device

upstream commmit: c2c789057f075022658b38b498755c29c1ba8055

According to acpi spec , the objectes of  _BCL and _BCM are required if
integrated LCD is present and supports brightness level and the _BQC is
the optional object. So the _BQC object will be ignored when the backlight
device is registered.
At the same time when there is no _BQC object, the current brightness will be
set to the maximum.

http://bugzilla.kernel.org/show_bug.cgi?id=10206

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Zhang Rui  <rui.zhang@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index d089c4519d456a796287ae9bfd77ad08d5f753f6..004da4d0063d4dfdfd98cbfb83da3f5efd9d96a2 100644 (file)
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -720,7 +720,7 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
 
        kfree(obj);
 
-       if (device->cap._BCL && device->cap._BCM && device->cap._BQC && max_level > 0){
+       if (device->cap._BCL && device->cap._BCM && max_level > 0) {
                int result;
                static int count = 0;
                char *name;
@@ -732,7 +732,17 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
                device->backlight = backlight_device_register(name,
                        NULL, device, &acpi_backlight_ops);
                device->backlight->props.max_brightness = device->brightness->count-3;
-               device->backlight->props.brightness = acpi_video_get_brightness(device->backlight);
+               /*
+                * If there exists the _BQC object, the _BQC object will be
+                * called to get the current backlight brightness. Otherwise
+                * the brightness will be set to the maximum.
+                */
+               if (device->cap._BQC)
+                       device->backlight->props.brightness =
+                               acpi_video_get_brightness(device->backlight);
+               else
+                       device->backlight->props.brightness =
+                               device->backlight->props.max_brightness;
                backlight_update_status(device->backlight);
                kfree(name);