Merge pull request #1479 from emersion/lost-crtc-state

backend/drm: fix state for outputs loosing their CRTC

backend/drm/drm.c

@@ -391,6 +391,8 @@ static void attempt_enable_needs_modeset(struct wlr_drm_backend *drm) {
 		if (conn->state == WLR_DRM_CONN_NEEDS_MODESET &&
 				conn->crtc != NULL && conn->desired_mode != NULL &&
 				conn->desired_enabled) {
+			wlr_log(WLR_DEBUG, "Output %s has a desired mode and a CRTC, "
+				"attempting a modeset", conn->output.name);
 			drm_connector_set_mode(&conn->output, conn->desired_mode);
 		}
 	}
@@ -981,8 +983,17 @@ static void realloc_crtcs(struct wlr_drm_backend *drm, bool *changed_outputs) {
 		i++;
 		struct wlr_output_mode *mode = conn->output.current_mode;
 
-		if (conn->state != WLR_DRM_CONN_CONNECTED || !changed_outputs[i]
-				|| conn->crtc == NULL) {
+		if (conn->state != WLR_DRM_CONN_CONNECTED || !changed_outputs[i]) {
+			continue;
+		}
+
+		if (conn->crtc == NULL) {
+			wlr_log(WLR_DEBUG, "Output has %s lost its CRTC",
+				conn->output.name);
+			conn->state = WLR_DRM_CONN_NEEDS_MODESET;
+			wlr_output_update_enabled(&conn->output, false);
+			conn->desired_mode = conn->output.current_mode;
+			wlr_output_update_mode(&conn->output, NULL);
 			continue;
 		}
 

types/wlr_output.c

@@ -173,8 +173,12 @@ bool wlr_output_set_custom_mode(struct wlr_output *output, int32_t width,
 void wlr_output_update_mode(struct wlr_output *output,
 		struct wlr_output_mode *mode) {
 	output->current_mode = mode;
+	if (mode != NULL) {
 		wlr_output_update_custom_mode(output, mode->width, mode->height,
 			mode->refresh);
+	} else {
+		wlr_output_update_custom_mode(output, 0, 0, 0);
+	}
 }
 
 void wlr_output_update_custom_mode(struct wlr_output *output, int32_t width,