From: Aaron Sowry <aaron@aeneby.se>

Avoid confusing userspace by not publishing backlight controls if ACPI equivalents are available.
Signed-off-by: Aaron Sowry <aaron@aeneby.se>
---
--- linux-2.6/drivers/gpu/drm/nouveau/nouveau_state.c.orig      2010-11-03 09:56:29.502828966 +0100
+++ linux-2.6/drivers/gpu/drm/nouveau/nouveau_state.c   2010-11-03 10:46:27.765829000 +0100
@@ -23,6 +23,7 @@
  * DEALINGS IN THE SOFTWARE.
  */

+#include <linux/acpi.h>
 #include <linux/swab.h>
 #include <linux/slab.h>
 #include "drmP.h"
@@ -648,9 +649,14 @@ nouveau_card_init(struct drm_device *dev
                        goto out_fence;
        }

-       ret = nouveau_backlight_init(dev);
-       if (ret)
-               NV_ERROR(dev, "Error %d registering backlight\n", ret);
+       if (acpi_video_backlight_support())
+               NV_INFO(dev, "Detected ACPI backlight support, "
+                               "not registering interface\n");
+       else {
+               ret = nouveau_backlight_init(dev);
+               if (ret)
+                       NV_ERROR(dev, "Error %d registering backlight\n", ret);
+       }

        nouveau_fbcon_init(dev);
        drm_kms_helper_poll_init(dev);