[PATCH 05/14] drm/nouveau: Don't register backlight when another backlight should be used

[Hans de Goede]

Before this commit when we want userspace to use the acpi_video backlight
device we register both the GPU's native backlight device and acpi_video's
firmware acpi_video# backlight device. This relies on userspace preferring
firmware type backlight devices over native ones.

Registering 2 backlight devices for a single display really is
undesirable, don't register the GPU's native backlight device when
another backlight device should be used.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_backlight.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index daf9f87477ba..f56ff797c78c 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -34,6 +34,8 @@
 #include <linux/backlight.h>
 #include <linux/idr.h>
 
+#include <acpi/video.h>
+
 #include "nouveau_drv.h"
 #include "nouveau_reg.h"
 #include "nouveau_encoder.h"
@@ -404,6 +406,11 @@ nouveau_backlight_init(struct drm_connector *connector)
 		goto fail_alloc;
 	}
 
+	if (acpi_video_get_backlight_type(true) != acpi_backlight_native) {
+		NV_INFO(drm, "Skipping nv_backlight registration\n");
+		goto fail_alloc;
+	}
+
 	if (!nouveau_get_backlight_name(backlight_name, bl)) {
 		NV_ERROR(drm, "Failed to retrieve a unique name for the backlight interface\n");
 		goto fail_alloc;
-- 
2.36.0