drm/arm/hdlcd: Reject atomic commits that disable only the plane

The HDLCD engine needs an active plane while the CRTC is active, as
it will start scanning out data from HDLCD_REG_FB_BASE once it gets
enabled. Make sure that the only available plane doesn't get disabled
while the CRTC remains active, as this will scanout invalid data.

Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

drivers/gpu/drm/arm/hdlcd_crtc.c

@@ -229,6 +229,8 @@ static const struct drm_crtc_helper_funcs hdlcd_crtc_helper_funcs = {
 static int hdlcd_plane_atomic_check(struct drm_plane *plane,
 				    struct drm_plane_state *state)
 {
+	int i;
+	struct drm_crtc *crtc;
 	struct drm_crtc_state *crtc_state;
 	u32 src_h = state->src_h >> 16;
 
@@ -238,20 +240,17 @@ static int hdlcd_plane_atomic_check(struct drm_plane *plane,
 		return -EINVAL;
 	}
 
-	if (!state->fb || !state->crtc)
-		return 0;
-
-	crtc_state = drm_atomic_get_existing_crtc_state(state->state,
-							state->crtc);
-	if (!crtc_state) {
-		DRM_DEBUG_KMS("Invalid crtc state\n");
-		return -EINVAL;
+	for_each_new_crtc_in_state(state->state, crtc, crtc_state, i) {
+		/* we cannot disable the plane while the CRTC is active */
+		if (!state->fb && crtc_state->active)
+			return -EINVAL;
+		return drm_atomic_helper_check_plane_state(state, crtc_state,
+						DRM_PLANE_HELPER_NO_SCALING,
+						DRM_PLANE_HELPER_NO_SCALING,
+						false, true);
 	}
 
-	return drm_atomic_helper_check_plane_state(state, crtc_state,
-						   DRM_PLANE_HELPER_NO_SCALING,
-						   DRM_PLANE_HELPER_NO_SCALING,
-						   false, true);
+	return 0;
 }
 
 static void hdlcd_plane_atomic_update(struct drm_plane *plane,

drivers/gpu/drm/arm/hdlcd_drv.c

@@ -325,6 +325,7 @@ err_fbdev:
 err_vblank:
 	pm_runtime_disable(drm->dev);
 err_pm_active:
+	drm_atomic_helper_shutdown(drm);
 	component_unbind_all(dev, drm);
 err_unload:
 	of_node_put(hdlcd->crtc.port);
@@ -350,16 +351,18 @@ static void hdlcd_drm_unbind(struct device *dev)
 	component_unbind_all(dev, drm);
 	of_node_put(hdlcd->crtc.port);
 	hdlcd->crtc.port = NULL;
-	pm_runtime_get_sync(drm->dev);
+	pm_runtime_get_sync(dev);
+	drm_crtc_vblank_off(&hdlcd->crtc);
 	drm_irq_uninstall(drm);
-	pm_runtime_put_sync(drm->dev);
-	pm_runtime_disable(drm->dev);
-	of_reserved_mem_device_release(drm->dev);
 	drm_atomic_helper_shutdown(drm);
+	pm_runtime_put(dev);
+	if (pm_runtime_enabled(dev))
+		pm_runtime_disable(dev);
+	of_reserved_mem_device_release(dev);
 	drm_mode_config_cleanup(drm);
-	drm_dev_put(drm);
 	drm->dev_private = NULL;
 	dev_set_drvdata(dev, NULL);
+	drm_dev_put(drm);
 }
 
 static const struct component_master_ops hdlcd_master_ops = {