intel/display: support stop/wakeup protocol

Issue #5344

repos/pc/src/driver/framebuffer/intel/pc/lx_i915.h

@@ -33,10 +33,12 @@ struct genode_mode {
 	char name[32];
 };
 
-int  lx_emul_i915_blit(unsigned);
+int  lx_emul_i915_blit(unsigned const connector_id, char const may_sleep);
+void lx_emul_i915_wakeup(unsigned connector_id);
 void lx_emul_i915_report_discrete(void * genode_xml);
 void lx_emul_i915_report_non_discrete(void * genode_xml);
 void lx_emul_i915_hotplug_connector(void);
+
 void lx_emul_i915_report_connector(void * lx_data, void * genode_xml,
                                    char const *name, char connected,
                                    unsigned brightness,

repos/pc/src/driver/framebuffer/intel/pc/lx_user.c

@@ -837,25 +837,67 @@ static void mark_framebuffer_dirty(struct drm_framebuffer * const fb)
 }
 
 
+/* track per connector (16 max) the empty capture attempts before stopping */
+enum { CAPTURE_RATE_MS = 10, ATTEMPTS_BEFORE_STOP = 7 };
+static unsigned unchanged[16] = { };
+
+void lx_emul_i915_wakeup(unsigned const connector_id)
+{
+	bool const valid_id  = connector_id < sizeof(unchanged) / sizeof(*unchanged);
+
+	if (!valid_id) {
+		printk("%s: connector id invalid %d\n", __func__, connector_id);
+		return;
+	}
+
+	unchanged[connector_id] = 0;
+
+	/* wake potential sleeping update task */
+	lx_emul_task_unblock(lx_update_task);
+}
+
+
 static int update_content(void *)
 {
 	while (true) {
 		struct drm_connector_list_iter  conn_iter;
-		struct drm_connector           *connector = NULL;
+		struct drm_connector           *connector  = NULL;
-		struct drm_device const        *dev       = dev_client->dev;
+		struct drm_device const        *dev        = dev_client->dev;
+		bool                            block_task = true;
 
 		drm_connector_list_iter_begin(dev, &conn_iter);
 		drm_client_for_each_connector_iter(connector, &conn_iter) {
+
 			struct drm_modeset_acquire_ctx  ctx;
 			struct drm_framebuffer         *fb  = NULL;
-			int                             err = -1;
+
+			int        err       = -1;
+			bool       may_sleep = false;
+			bool const valid_id  = connector->index < sizeof(unchanged) / sizeof(*unchanged);
 
 			if (connector->status != connector_status_connected)
 				continue;
 
-			if (!lx_emul_i915_blit(connector->index))
+			if (valid_id) {
+				unchanged[connector->index] ++;
+
+				if (unchanged[connector->index] > ATTEMPTS_BEFORE_STOP)
+					continue;
+			}
+			else
+				printk("%s: connector id invalid %d\n", __func__, connector->index);
+
+			block_task = false;
+
+			if (valid_id)
+				may_sleep = unchanged[connector->index] >= ATTEMPTS_BEFORE_STOP;
+
+			if (!lx_emul_i915_blit(connector->index, may_sleep))
 				continue;
 
+			if (valid_id)
+				unchanged[connector->index] = 0;
+
 			if (!connector->state || !connector->state->crtc)
 				continue;
 
@@ -872,8 +914,11 @@ static int update_content(void *)
 		}
 		drm_connector_list_iter_end(&conn_iter);
 
-		/* schedule_timeout(jiffes) or hrtimer or msleep */
+		if (block_task)
-		msleep(20);
+			lx_emul_task_schedule(true /* block task */);
+		else
+			/* schedule_timeout(jiffes) or hrtimer or msleep */
+			msleep(CAPTURE_RATE_MS);
 	}
 
 	return 0;

repos/pc/src/driver/framebuffer/intel/pc/main.cc

@@ -67,9 +67,8 @@ struct Framebuffer::Driver
 		using Space = Id_space<Connector>;
 		using Id    = Space::Id;
 
-		Space::Element id_element;
+		Space::Element            id_element;
-
+		Signal_handler<Connector> capture_wakeup;
-		Connector(Space &space, Id id) : id_element(*this, space, id) { }
 
 		addr_t        base      { };
 		Capture::Area size      { };
@@ -78,11 +77,23 @@ struct Framebuffer::Driver
 
 		Constructible<Capture::Connection>         capture { };
 		Constructible<Capture::Connection::Screen> screen  { };
+
+		Connector(Env &env, Space &space, Id id)
+		:
+			id_element(*this, space, id),
+			capture_wakeup(env.ep(), *this, &Connector::wakeup_handler)
+		{ }
+
+		void wakeup_handler()
+		{
+			lx_emul_i915_wakeup(unsigned(id_element.id().value));
+			Lx_kit::env().scheduler.execute();
+		}
 	};
 
 	Connector::Space ids { };
 
-	bool capture(Connector::Space &ids, Connector::Id const &id)
+	bool capture(Connector::Space &ids, Connector::Id const &id, bool const may_stop)
 	{
 		using Pixel = Capture::Pixel;
 
@@ -109,6 +120,10 @@ struct Framebuffer::Driver
 					dirty = true;
 				});
 			});
+
+			if (!dirty && may_stop)
+				connector.capture->capture_stopped();
+
 		}, [&](){ /* unknown connector id */ });
 
 		return dirty;
@@ -136,6 +151,8 @@ struct Framebuffer::Driver
 			Capture::Connection::Screen::Attr attr = { .px = conn.size, .mm = conn.size_mm };
 			conn.capture.construct(env, label);
 			conn.screen .construct(*conn.capture, env.rm(), attr);
+
+			conn.capture->wakeup_sigh(conn.capture_wakeup);
 		} else {
 			conn.screen .destruct();
 			conn.capture.destruct();
@@ -450,7 +467,9 @@ void lx_emul_i915_framebuffer_ready(unsigned const connector_id,
 		if (!base)
 			return;
 
-		new (drv.heap) Connector (drv.ids, id);
+		new (drv.heap) Connector (env, drv.ids, id);
+
+		lx_emul_i915_wakeup(unsigned(id.value));
 	});
 
 	drv.ids.apply<Connector>(id, [&](Connector &conn) {
@@ -549,13 +568,13 @@ void lx_emul_i915_report_modes(void * genode_xml, struct genode_mode *mode)
 }
 
 
-int lx_emul_i915_blit(unsigned connector_id)
+int lx_emul_i915_blit(unsigned const connector_id, char const may_stop)
 {
 	auto &drv = driver(Lx_kit::env().env);
 
 	auto const id = Framebuffer::Driver::Connector::Id { connector_id };
 
-	return drv.capture(drv.ids, id);
+	return drv.capture(drv.ids, id, may_stop);
 }