DPMS support

backend/drm/backend.c

@@ -101,3 +101,11 @@ error_backend:
 	free(backend);
 	return NULL;
 }
+
+void wlr_drm_backend_dpms(struct wlr_backend *backend, bool screen_on) {
+	struct wlr_backend_state *state = backend->state;
+	for (size_t i = 0; i < state->outputs->length; ++i) {
+		struct wlr_output_state *output = state->outputs->items[i];
+		wlr_drm_output_dpms(state->fd, output, screen_on);
+	}
+}

backend/drm/drm.c

@@ -249,6 +249,30 @@ static struct wlr_output_impl output_impl = {
 	.destroy = wlr_drm_output_destroy,
 };
 
+static void scan_property_ids(int fd, drmModeConnector *conn,
+		struct wlr_output_state *output) {
+	for (int i = 0; i < conn->count_props; ++i) {
+		drmModePropertyRes *prop = drmModeGetProperty(fd, conn->props[i]);
+		if (!prop) {
+			continue;
+		}
+
+		// I think this is guranteed to exist
+		if (strcmp(prop->name, "DPMS") == 0) {
+			output->props.dpms = prop->prop_id;
+
+			/* There may be more properties we want to get,
+			 * but since it's currently only this, we exit early
+			 */
+
+			drmModeFreeProperty(prop);
+			break;
+		}
+
+		drmModeFreeProperty(prop);
+	}
+}
+
 void wlr_drm_scan_connectors(struct wlr_backend_state *state) {
 	wlr_log(L_INFO, "Scanning DRM connectors");
 
@@ -300,6 +324,8 @@ void wlr_drm_scan_connectors(struct wlr_backend_state *state) {
 				free(curr_enc);
 			}
 
+			scan_property_ids(state->fd, conn, output);
+
 			list_add(state->outputs, output);
 			wlr_log(L_INFO, "Found display '%s'", output->name);
 		} else {
@@ -416,3 +442,23 @@ void wlr_drm_output_cleanup(struct wlr_output_state *output, bool restore) {
 	}
 	// TODO: free wlr_output
 }
+
+void wlr_drm_output_dpms(int fd, struct wlr_output_state *output, bool screen_on) {
+	if (output->state != DRM_OUTPUT_CONNECTED) {
+		return;
+	}
+
+	if (screen_on) {
+		drmModeConnectorSetProperty(fd, output->connector, output->props.dpms,
+			DRM_MODE_DPMS_ON);
+
+		// Start rendering loop again by drawing a black frame
+		wlr_drm_output_begin(output->wlr_output);
+		glClearColor(0.0, 0.0, 0.0, 1.0);
+		glClear(GL_COLOR_BUFFER_BIT);
+		wlr_drm_output_end(output->wlr_output);
+	} else {
+		drmModeConnectorSetProperty(fd, output->connector, output->props.dpms,
+			DRM_MODE_DPMS_STANDBY);
+	}
+}

example/main.c

@@ -81,6 +81,18 @@ int timer_done(void *data) {
 	return 1;
 }
 
+int dpms_on(void *data) {
+	struct wlr_backend *backend = data;
+	wlr_drm_backend_dpms(backend, false);
+	return 1;
+}
+
+int dpms_off(void *data) {
+	struct wlr_backend *backend = data;
+	wlr_drm_backend_dpms(backend, true);
+	return 1;
+}
+
 int main() {
 	if (getenv("DISPLAY")) {
 		fprintf(stderr, "Detected that X is running. Run this in its own virtual terminal.\n");
@@ -120,8 +132,14 @@ int main() {
 	bool done = false;
 	struct wl_event_source *timer = wl_event_loop_add_timer(event_loop,
 		timer_done, &done);
+	struct wl_event_source *timer_dpms_on = wl_event_loop_add_timer(event_loop,
+		dpms_on, wlr);
+	struct wl_event_source *timer_dpms_off = wl_event_loop_add_timer(event_loop,
+		dpms_off, wlr);
 
-	wl_event_source_timer_update(timer, 5000);
+	wl_event_source_timer_update(timer, 20000);
+	wl_event_source_timer_update(timer_dpms_on, 5000);
+	wl_event_source_timer_update(timer_dpms_off, 10000);
 
 	while (!done) {
 		wl_event_loop_dispatch(event_loop, 0);

include/backend/drm/drm.h

@@ -36,6 +36,10 @@ struct wlr_output_state {
 	uint32_t connector;
 	char name[16];
 
+	struct {
+		uint32_t dpms;
+	} props;
+
 	uint32_t width;
 	uint32_t height;
 
@@ -51,6 +55,7 @@ struct wlr_output_state {
 };
 
 void wlr_drm_output_cleanup(struct wlr_output_state *output, bool restore);
+void wlr_drm_output_dpms(int fd, struct wlr_output_state *output, bool screen_on);
 
 void wlr_drm_scan_connectors(struct wlr_backend_state *state);
 int wlr_drm_event(int fd, uint32_t mask, void *data);

include/wlr/backend/drm.h

@@ -10,6 +10,8 @@
 struct wlr_backend *wlr_drm_backend_create(struct wl_display *display,
 	struct wlr_session *session);
 
+void wlr_drm_backend_dpms(struct wlr_backend *backend, bool screen_on);
+
 void wlr_drm_output_begin(struct wlr_output *out);
 void wlr_drm_output_end(struct wlr_output *out);