drm/omap: Add support for drm_panel

Hook up drm_panel support in the omapdrm driver. The change is
relatively simply as the way has been paved by drm_bridge support
already. In addition to looking up, attaching to and detaching from the
panel, we only need to add panel support in the connector .get_modes()
handler, take connector bus flags (set by the panel) into account, and
enable/disable the panel in the encoder enable/disable operations
handlers.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/gpu/drm/omapdrm/omap_connector.c b/drivers/gpu/drm/omapdrm/omap_connector.c
index f711a26..5967283 100644
--- a/drivers/gpu/drm/omapdrm/omap_connector.c
+++ b/drivers/gpu/drm/omapdrm/omap_connector.c
@@ -17,6 +17,7 @@
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc.h>
+#include <drm/drm_panel.h>
 #include <drm/drm_probe_helper.h>
 
 #include "omap_drv.h"
@@ -211,6 +212,7 @@
 
 static int omap_connector_get_modes(struct drm_connector *connector)
 {
+	struct omap_connector *omap_connector = to_omap_connector(connector);
 	struct omap_dss_device *dssdev;
 
 	DBG("%s", connector->name);
@@ -234,6 +236,13 @@
 		return dssdev->ops->get_modes(dssdev, connector);
 
 	/*
+	 * Otherwise if the display pipeline uses a drm_panel, we delegate the
+	 * operation to the panel API.
+	 */
+	if (omap_connector->output->panel)
+		return drm_panel_get_modes(omap_connector->output->panel);
+
+	/*
 	 * We can't retrieve modes, which can happen for instance for a DVI or
 	 * VGA output with the DDC bus unconnected. The KMS core will add the
 	 * default modes.