ACPI: video: Loosen strictness of video bus detection code

BugLink: http://bugs.launchpad.net/bugs/333386

Currently a video bus device must (beside other criteria) define _DOD and
_DOS methods to be considered a video device.
Some broken BIOSes prevented working backlight control by only defining both
for one (non-existing bus) and only _DOD for the rest. With this patch in
place the other bus definitions were considered too and backlight control
started to work again.

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 7 insertions, 2 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index f6e54bf8dd96..64e3c581b7a9 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -1109,7 +1109,12 @@ static int acpi_video_bus_check(struct acpi_video_bus *video)
          */
 
         /* Does this device support video switching? */
-        if (video->cap._DOS) {
+        if (video->cap._DOS || video->cap._DOD) {
+                if (!video->cap._DOS) {
+                        printk(KERN_WARNING FW_BUG
+                                "ACPI(%s) defines _DOD but not _DOS\n",
+                                acpi_device_bid(video->device));
+                }
                 video->flags.multihead = 1;
                 status = 0;
         }
diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 7032f25da9b5..575593a8b4e6 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -84,7 +84,7 @@ long acpi_is_video_device(struct acpi_device *device)
                 return 0;
 
         /* Does this device able to support video switching ? */
-        if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOD", &h_dummy)) &&
+        if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOD", &h_dummy)) ||
             ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOS", &h_dummy)))
                 video_caps |= ACPI_VIDEO_OUTPUT_SWITCHING;