drm/armada: enable atomic modeset support

Enable atomic modeset helpers, and internal DRM use of atomic modeset
with armada-drm.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

drivers/gpu/drm/armada/armada_crtc.c

@@ -278,13 +278,12 @@ static void armada_drm_crtc_prepare(struct drm_crtc *crtc)
 	struct drm_plane *plane;
 
 	/*
-	 * If we have an overlay plane associated with this CRTC, disable
-	 * it before the modeset to avoid its coordinates being outside
-	 * the new mode parameters.
+	 * If we have an overlay plane associated with this CRTC, disable it
+	 * before the modeset to avoid its coordinates being outside the new
+	 * mode parameters.  For transitional atomic modeset, we only wait.
 	 */
 	plane = dcrtc->plane;
 	if (plane) {
-		drm_plane_force_disable(plane);
 		WARN_ON(!armada_drm_plane_work_wait(drm_to_armada_plane(plane),
 						    HZ));
 	}

drivers/gpu/drm/armada/armada_drv.c

@@ -9,6 +9,7 @@
 #include <linux/component.h>
 #include <linux/module.h>
 #include <linux/of_graph.h>
+#include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_of.h>
@@ -73,7 +74,7 @@ static struct drm_driver armada_drm_driver = {
 	.desc			= "Armada SoC DRM",
 	.date			= "20120730",
 	.driver_features	= DRIVER_GEM | DRIVER_MODESET |
-				  DRIVER_PRIME,
+				  DRIVER_PRIME | DRIVER_ATOMIC,
 	.ioctls			= armada_ioctls,
 	.fops			= &armada_drm_fops,
 };
@@ -81,6 +82,8 @@ static struct drm_driver armada_drm_driver = {
 static const struct drm_mode_config_funcs armada_drm_mode_config_funcs = {
 	.fb_create		= armada_fb_create,
 	.output_poll_changed	= drm_fb_helper_output_poll_changed,
+	.atomic_check		= drm_atomic_helper_check,
+	.atomic_commit		= drm_atomic_helper_commit,
 };
 
 static int armada_drm_bind(struct device *dev)