drm/atomic-helper: Add NO_DISABLE_AFTER_MODESET flag support for plane commit

Drivers may set the NO_DISABLE_AFTER_MODESET flag in the 'flags' parameter
of the helper drm_atomic_helper_commit_planes() if the relevant display
controllers(e.g., IPUv3 for imx-drm) require to disable a CRTC's planes
when the CRTC is disabled. The helper would skip the ->atomic_disable
call for a plane if the CRTC of the old plane state needs a modesetting
operation. Of course, the drivers need to disable the planes in their CRTC
disable callbacks since no one else would do that.

Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Peter Senna Tschudin <peter.senna@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Liu Ying <gnuiyl@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1472461923-14364-1-git-send-email-gnuiyl@gmail.com

drivers/gpu/drm/mediatek/mtk_drm_drv.c

@@ -70,13 +70,15 @@ static void mtk_atomic_complete(struct mtk_drm_private *private,
 	 *
 	 *     drm_atomic_helper_commit_modeset_disables(dev, state);
 	 *     drm_atomic_helper_commit_modeset_enables(dev, state);
-	 *     drm_atomic_helper_commit_planes(dev, state, true);
+	 *     drm_atomic_helper_commit_planes(dev, state,
+	 *                                     DRM_PLANE_COMMIT_ACTIVE_ONLY);
 	 *
 	 * See the kerneldoc entries for these three functions for more details.
 	 */
 	drm_atomic_helper_commit_modeset_disables(drm, state);
 	drm_atomic_helper_commit_modeset_enables(drm, state);
-	drm_atomic_helper_commit_planes(drm, state, true);
+	drm_atomic_helper_commit_planes(drm, state,
+					DRM_PLANE_COMMIT_ACTIVE_ONLY);
 
 	drm_atomic_helper_wait_for_vblanks(drm, state);