drm/nouveau: don't expose backlight control when available through ACPI

Avoid confusing userspace by not publishing backlight controls if ACPI
equivalents are available.

Reported-by: Aaron Sowry <aaron@aeneby.se>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index 406228f..b14c811 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -31,6 +31,7 @@
  */
 
 #include <linux/backlight.h>
+#include <linux/acpi.h>
 
 #include "drmP.h"
 #include "nouveau_drv.h"
@@ -136,6 +137,14 @@ int nouveau_backlight_init(struct drm_device *dev)
 {
        struct drm_nouveau_private *dev_priv = dev->dev_private;
 
+#ifdef CONFIG_ACPI
+       if (acpi_video_backlight_support()) {
+               NV_INFO(dev, "ACPI backlight interface available, "
+                            "not registering our own\n");
+               return 0;
+       }
+#endif
+
        switch (dev_priv->card_type) {
        case NV_40:
                return nouveau_nv40_backlight_init(dev);