drm/amd/display: Create plane rotation property

It's otherwise properly supported, just needs exposing to userspace.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Pierre-Loup A. Griffais <pgriffais@valvesoftware.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -5866,6 +5866,7 @@ static int amdgpu_dm_plane_init(struct amdgpu_display_manager *dm,
 	uint32_t formats[32];
 	int num_formats;
 	int res = -EPERM;
+	unsigned int supported_rotations;
 
 	num_formats = get_plane_formats(plane, plane_cap, formats,
 					ARRAY_SIZE(formats));
@@ -5900,6 +5901,13 @@ static int amdgpu_dm_plane_init(struct amdgpu_display_manager *dm,
 			DRM_COLOR_YCBCR_BT709, DRM_COLOR_YCBCR_LIMITED_RANGE);
 	}
 
+	supported_rotations =
+		DRM_MODE_ROTATE_0 | DRM_MODE_ROTATE_90 |
+		DRM_MODE_ROTATE_180 | DRM_MODE_ROTATE_270;
+
+	drm_plane_create_rotation_property(plane, DRM_MODE_ROTATE_0,
+					   supported_rotations);
+
 	drm_plane_helper_add(plane, &dm_plane_helper_funcs);
 
 	/* Create (reset) the plane state */