drm/atmel-hlcdc: Stop using plane->fb

We want to get rid of plane->fb on atomic drivers. Stop looking at it.

Daniel pointed out that the drm_framebuffer_put() in the plane cleanup
indicates that the driver doesn't shut things down cleanly. To do
that we should be able to just call drm_atomic_helper_shutdown(). Not
really sure the current cleanup sequence is actually sane, but whatever.

v2: Replace the drm_framebuffer_put() with
    drm_atomic_helper_shutdown() (Daniel)

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180405151400.11326-10-ville.syrjala@linux.intel.comReviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c

@@ -681,6 +681,7 @@ static void atmel_hlcdc_dc_unload(struct drm_device *dev)
 	drm_fb_cma_fbdev_fini(dev);
 	flush_workqueue(dc->wq);
 	drm_kms_helper_poll_fini(dev);
+	drm_atomic_helper_shutdown(dev);
 	drm_mode_config_cleanup(dev);
 
 	pm_runtime_get_sync(dev->dev);

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c

@@ -817,16 +817,6 @@ static void atmel_hlcdc_plane_atomic_disable(struct drm_plane *p,
 	atmel_hlcdc_layer_read_reg(&plane->layer, ATMEL_HLCDC_LAYER_ISR);
 }
 
-static void atmel_hlcdc_plane_destroy(struct drm_plane *p)
-{
-	struct atmel_hlcdc_plane *plane = drm_plane_to_atmel_hlcdc_plane(p);
-
-	if (plane->base.fb)
-		drm_framebuffer_put(plane->base.fb);
-
-	drm_plane_cleanup(p);
-}
-
 static int atmel_hlcdc_plane_init_properties(struct atmel_hlcdc_plane *plane)
 {
 	const struct atmel_hlcdc_layer_desc *desc = plane->layer.desc;
@@ -1003,7 +993,7 @@ static void atmel_hlcdc_plane_atomic_destroy_state(struct drm_plane *p,
 static const struct drm_plane_funcs layer_plane_funcs = {
 	.update_plane = drm_atomic_helper_update_plane,
 	.disable_plane = drm_atomic_helper_disable_plane,
-	.destroy = atmel_hlcdc_plane_destroy,
+	.destroy = drm_plane_cleanup,
 	.reset = atmel_hlcdc_plane_reset,
 	.atomic_duplicate_state = atmel_hlcdc_plane_atomic_duplicate_state,
 	.atomic_destroy_state = atmel_hlcdc_plane_atomic_destroy_state,