Manage power only during capturing

This makes it possible for power management software to run in the
system while wayvnc is running.

The wlr-output-power-management-v1 protocol gives exclusive access to
whichever client that holds an output-power object. Holding it while
the process is running, precludes other clients from managing power.

include/output.h

@@ -68,8 +68,9 @@ struct output {
 
 struct output* output_new(struct wl_output* wl_output, uint32_t id);
 void output_destroy(struct output* output);
-void output_setup_wl_managers(struct wl_list* list);
-int output_set_power_state(struct output* output, enum output_power_state state);
+void output_setup_xdg_output_managers(struct wl_list* list);
+int output_acquire_power_on(struct output* output);
+void output_release_power_on(struct output* output);
 void output_list_destroy(struct wl_list* list);
 struct output* output_find_by_id(struct wl_list* list, uint32_t id);
 struct output* output_find_by_name(struct wl_list* list, const char* name);

src/main.c

@@ -254,15 +254,14 @@ static void registry_add(void* data, struct wl_registry* registry,
 			wl_registry_bind(registry, id,
 			                 &zxdg_output_manager_v1_interface, 3);
 
-		output_setup_wl_managers(&self->outputs);
+		output_setup_xdg_output_managers(&self->outputs);
 		return;
 	}
 
 	if (strcmp(interface, zwlr_output_power_manager_v1_interface.name) == 0) {
 		nvnc_trace("Registering new wlr_output_power_manager");
 		wlr_output_power_manager = wl_registry_bind(registry, id,
 					&zwlr_output_power_manager_v1_interface, 1);
-		output_setup_wl_managers(&self->outputs);
 		return;
 	}
 
@@ -1001,15 +1000,20 @@ int wayvnc_start_capture_immediate(struct wayvnc* self)
 	if (self->capture_retry_timer)
 		return 0;
 
-	if (self->selected_output->power == OUTPUT_POWER_OFF) {
-		nvnc_log(NVNC_LOG_WARNING, "Selected output is in powersaving mode. Delaying capture until it turns on.");
-		if (output_set_power_state(self->selected_output, OUTPUT_POWER_ON)
-				== 0)
-			nvnc_log(NVNC_LOG_WARNING, "Requested power ON.");
+	struct output* output = self->selected_output;
+	int rc = output_acquire_power_on(output);
+	if (rc == 0) {
+		nvnc_log(NVNC_LOG_DEBUG, "Acquired power state management. Waiting for power event to start capturing");
 		return 0;
+	} else if (rc > 0 && output->power != OUTPUT_POWER_ON) {
+		nvnc_log(NVNC_LOG_DEBUG, "Output power state management already acquired, but not yet powered on");
+		return 0;
+	} else if (rc < 0) {
+		nvnc_log(NVNC_LOG_WARNING, "Failed to acquire power state control. Capturing may fail.");
 	}
 
-	int rc = screencopy_start_immediate(&self->screencopy);
+	nvnc_log(NVNC_LOG_DEBUG, "screencopy_start_immediate");
+	rc = screencopy_start_immediate(&self->screencopy);
 	if (rc < 0) {
 		nvnc_log(NVNC_LOG_ERROR, "Failed to start capture. Exiting...");
 		wayvnc_exit(self);
@@ -1053,15 +1057,15 @@ void on_output_dimension_change(struct output* output)
 
 static void on_output_power_change(struct output* output)
 {
-	nvnc_trace("Output %s power state changed to %s", output->name, output_power_state_name(output->power));
+	nvnc_trace("Output %s power state changed to %s", output->name,
+			output_power_state_name(output->power));
 
 	struct wayvnc* self = output->userdata;
 	if (self->selected_output != output || self->nr_clients == 0)
 		return;
 
 	switch (output->power) {
 	case OUTPUT_POWER_ON:
-		nvnc_log(NVNC_LOG_WARNING, "Output is now on. Restarting frame capture");
 		wayvnc_start_capture_immediate(self);
 		break;
 	case OUTPUT_POWER_OFF:
@@ -1313,6 +1317,7 @@ static void client_destroy(void* obj)
 	if (wayvnc->nr_clients == 0 && wayvnc->display) {
 		nvnc_log(NVNC_LOG_INFO, "Stopping screen capture");
 		screencopy_stop(&wayvnc->screencopy);
+		output_release_power_on(wayvnc->selected_output);
 		stop_performance_ticker(wayvnc);
 	}
 
@@ -1553,6 +1558,7 @@ void switch_to_output(struct wayvnc* self, struct output* output)
 		return;
 	}
 	screencopy_stop(&self->screencopy);
+	output_release_power_on(output);
 	set_selected_output(self, output);
 	reinitialise_pointers(self);
 	if (self->nr_clients > 0)

src/output.c

@@ -184,6 +184,7 @@ static const struct wl_output_listener output_listener = {
 
 void output_destroy(struct output* output)
 {
+	output_release_power_on(output);
 	if (output->xdg_output)
 		zxdg_output_v1_destroy(output->xdg_output);
 	if (output->wlr_output_power)
@@ -307,34 +308,35 @@ static const struct zwlr_output_power_v1_listener wlr_output_power_listener = {
 	.failed = output_power_failed,
 };
 
-static void output_setup_wlr_output_power_manager(struct output* self)
+int output_acquire_power_on(struct output* output)
 {
-	if (!wlr_output_power_manager || self->wlr_output_power)
-		return;
+	if (output->wlr_output_power)
+		return 1;
+
+	if (!wlr_output_power_manager)
+		return -1;
 
 	struct zwlr_output_power_v1* wlr_output_power =
 		zwlr_output_power_manager_v1_get_output_power(
-				wlr_output_power_manager,
-				self->wl_output);
-	self->wlr_output_power = wlr_output_power;
+				wlr_output_power_manager, output->wl_output);
+	output->wlr_output_power = wlr_output_power;
+
+	zwlr_output_power_v1_add_listener(output->wlr_output_power,
+			&wlr_output_power_listener, output);
 
-	zwlr_output_power_v1_add_listener(self->wlr_output_power,
-			&wlr_output_power_listener, self);
+	zwlr_output_power_v1_set_mode(output->wlr_output_power,
+		ZWLR_OUTPUT_POWER_V1_MODE_ON);
+	return 0;
 }
 
-int output_set_power_state(struct output* output, enum output_power_state state)
+void output_release_power_on(struct output* output)
 {
-	assert(state != OUTPUT_POWER_UNKNOWN);
-	if (!output->wlr_output_power) {
-		errno = ENOENT;
-		return -1;
-	}
-	nvnc_trace("Output %s requesting power %s", output->name,
-			output_power_state_name(state));
-	int mode = (state == OUTPUT_POWER_ON) ? ZWLR_OUTPUT_POWER_V1_MODE_ON :
-		ZWLR_OUTPUT_POWER_V1_MODE_OFF;
-	zwlr_output_power_v1_set_mode(output->wlr_output_power, mode);
-	return 0;
+	if (!output->wlr_output_power)
+		return;
+
+	zwlr_output_power_v1_destroy(output->wlr_output_power);
+	output->wlr_output_power = NULL;
+	output->power = OUTPUT_POWER_UNKNOWN;
 }
 
 struct output* output_find_by_id(struct wl_list* list, uint32_t id)
@@ -386,12 +388,11 @@ struct output* output_cycle(const struct wl_list* list,
 	return wl_container_of(iter, output, link);
 }
 
-void output_setup_wl_managers(struct wl_list* list)
+void output_setup_xdg_output_managers(struct wl_list* list)
 {
 	struct output* output;
 	wl_list_for_each(output, list, link) {
 		output_setup_xdg_output_manager(output);
-		output_setup_wlr_output_power_manager(output);
 	}
 }
 
@@ -411,7 +412,6 @@ struct output* output_new(struct wl_output* wl_output, uint32_t id)
 			output);
 
 	output_setup_xdg_output_manager(output);
-	output_setup_wlr_output_power_manager(output);
 
 	return output;
 }