drm: Make exposing stereo modes a per-connector opt-in

Just like with interlaced or double scan modes, make stereo modes a
per-connector opt-in to give a chance to driver authors to make it work
before enabling it.
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc_helper.c

@@ -76,7 +76,8 @@ static void drm_mode_validate_flag(struct drm_connector *connector,
 {
 	struct drm_display_mode *mode;
 
-	if (flags == (DRM_MODE_FLAG_DBLSCAN | DRM_MODE_FLAG_INTERLACE))
+	if (flags == (DRM_MODE_FLAG_DBLSCAN | DRM_MODE_FLAG_INTERLACE |
+		      DRM_MODE_FLAG_3D_MASK))
 		return;
 
 	list_for_each_entry(mode, &connector->modes, head) {
@@ -86,6 +87,9 @@ static void drm_mode_validate_flag(struct drm_connector *connector,
 		if ((mode->flags & DRM_MODE_FLAG_DBLSCAN) &&
 				!(flags & DRM_MODE_FLAG_DBLSCAN))
 			mode->status = MODE_NO_DBLESCAN;
+		if ((mode->flags & DRM_MODE_FLAG_3D_MASK) &&
+				!(flags & DRM_MODE_FLAG_3D_MASK))
+			mode->status = MODE_NO_STEREO;
 	}
 
 	return;
@@ -175,6 +179,8 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 		mode_flags |= DRM_MODE_FLAG_INTERLACE;
 	if (connector->doublescan_allowed)
 		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
+	if (connector->stereo_allowed)
+		mode_flags |= DRM_MODE_FLAG_3D_MASK;
 	drm_mode_validate_flag(connector, mode_flags);
 
 	list_for_each_entry(mode, &connector->modes, head) {

include/drm/drm_crtc.h

@@ -108,6 +108,7 @@ enum drm_mode_status {
     MODE_ONE_HEIGHT,    /* only one height is supported */
     MODE_ONE_SIZE,      /* only one resolution is supported */
     MODE_NO_REDUCED,    /* monitor doesn't accept reduced blanking */
+    MODE_NO_STEREO,	/* stereo modes not supported */
     MODE_UNVERIFIED = -3, /* mode needs to reverified */
     MODE_BAD = -2,	/* unspecified reason */
     MODE_ERROR	= -1	/* error condition */
@@ -611,6 +612,7 @@ struct drm_connector {
 	int connector_type_id;
 	bool interlace_allowed;
 	bool doublescan_allowed;
+	bool stereo_allowed;
 	struct list_head modes; /* list of modes on this connector */
 
 	enum drm_connector_status status;