[Nouveau] [PATCH REBASED 2/2] Do not register interface if Apple GMUX detected

[Pierre Moreau]

From: Pierre Moreau <pierre.morrow at free.fr>

The Apple GMUX is the one managing the backlight, so there is no need for
Nouveau to register its own backlight interface.

v2: Do not split information message on two lines as it prevents from grepping
    it, as pointed out by Lukas Wunner

Signed-off-by: Pierre Moreau <pierre.morrow at free.fr>
---
 drivers/gpu/drm/nouveau/nouveau_backlight.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index 0e69612..3c91c24 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -30,6 +30,7 @@
  * Register locations derived from NVClock by Roderick Colenbrander
  */
 
+#include <linux/apple-gmux.h>
 #include <linux/backlight.h>
 #include <linux/idr.h>
 
@@ -258,6 +259,11 @@ nouveau_backlight_init(struct drm_device *dev)
 	struct nvif_device *device = &drm->device;
 	struct drm_connector *connector;
 
+	if (apple_gmux_present()) {
+		NV_INFO(drm, "Apple GMUX detected: not registering Nouveau backlight interface");
+		return 0;
+	}
+
 	INIT_LIST_HEAD(&drm->bl_connectors);
 
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
-- 
2.10.2