fb_drv: implement 'buffered' mode for OMAP4

Fixes #1228.

repos/os/src/drivers/framebuffer/omap4/main.cc

@@ -17,6 +17,7 @@
 #include <dataspace/client.h>
 #include <base/printf.h>
 #include <base/sleep.h>
+#include <blit/blit.h>
 #include <os/config.h>
 #include <os/static_root.h>
 
@@ -34,12 +35,21 @@ class Framebuffer::Session_component : public Genode::Rpc_object<Framebuffer::Se
 {
 	private:
 
-		size_t _width;
-		size_t _height;
-		Driver::Format            _format;
-		size_t                    _size;
-		Dataspace_capability      _ds;
-		addr_t                    _phys_base;
+		size_t         _width;
+		size_t         _height;
+		bool           _buffered;
+		Mode           _mode;
+		Driver::Format _format;
+		size_t         _size;
+
+		/* dataspace uses a back buffer (if '_buffered' is true) */
+		Genode::Dataspace_capability _bb_ds;
+		void                        *_bb_addr;
+
+		/* dataspace of physical frame buffer */
+		Genode::Dataspace_capability _fb_ds;
+		void                        *_fb_addr;
+
 		Signal_context_capability _sync_sigh;
 
 		/**
@@ -53,19 +63,44 @@ class Framebuffer::Session_component : public Genode::Rpc_object<Framebuffer::Se
 			return Mode::INVALID;
 		}
 
+		void _refresh_buffered(int x, int y, int w, int h)
+		{
+			Mode _mode = mode();
+
+			/* clip specified coordinates against screen boundaries */
+			int x2 = min(x + w - 1, (int)_mode.width()  - 1),
+				y2 = min(y + h - 1, (int)_mode.height() - 1);
+			int x1 = max(x, 0),
+				y1 = max(y, 0);
+			if (x1 > x2 || y1 > y2) return;
+
+			int bypp = _mode.bytes_per_pixel();
+
+			/* copy pixels from back buffer to physical frame buffer */
+			char *src = (char *)_bb_addr + bypp*(_mode.width()*y1 + x1),
+			     *dst = (char *)_fb_addr + bypp*(_mode.width()*y1 + x1);
+
+			blit(src, bypp*_mode.width(), dst, bypp*_mode.width(),
+				 bypp*(x2 - x1 + 1), y2 - y1 + 1);
+		}
+
 	public:
 
 		Session_component(Driver &driver, size_t width, size_t height,
-			Driver::Output output)
-		:
-			_width(width),
-			_height(height),
-			_format(Driver::FORMAT_RGB565),
-			_size(driver.buffer_size(width, height, _format)),
-			_ds(env()->ram_session()->alloc(_size, WRITE_COMBINED)),
-			_phys_base(Dataspace_client(_ds).phys_addr())
+		                  Driver::Output output, bool buffered)
+		: _width(width),
+		  _height(height),
+		  _buffered(buffered),
+		  _format(Driver::FORMAT_RGB565),
+		  _size(driver.buffer_size(width, height, _format)),
+		  _bb_ds(buffered ? Genode::env()->ram_session()->alloc(_size)
+		                  : Genode::Ram_dataspace_capability()),
+		  _bb_addr(buffered ? (void*)Genode::env()->rm_session()->attach(_bb_ds) : 0),
+		  _fb_ds(Genode::env()->ram_session()->alloc(_size, WRITE_COMBINED)),
+		  _fb_addr((void*)Genode::env()->rm_session()->attach(_fb_ds))
 		{
-			if (!driver.init(width, height, _format, output, _phys_base)) {
+			if (!driver.init(width, height, _format, output,
+				Dataspace_client(_fb_ds).phys_addr())) {
 				PERR("Could not initialize display");
 				struct Could_not_initialize_display : Exception { };
 				throw Could_not_initialize_display();
@@ -76,7 +111,10 @@ class Framebuffer::Session_component : public Genode::Rpc_object<Framebuffer::Se
 		 ** Framebuffer::Session interface **
 		 ************************************/
 
-		Dataspace_capability dataspace() override { return _ds; }
+		Dataspace_capability dataspace() override
+		{
+			return _buffered ? _bb_ds : _fb_ds;
+		}
 
 		Mode mode() const override
 		{
@@ -92,14 +130,28 @@ class Framebuffer::Session_component : public Genode::Rpc_object<Framebuffer::Se
 			_sync_sigh = sigh;
 		}
 
-		void refresh(int, int, int, int) override
+		void refresh(int x, int y, int w, int h) override
 		{
+			if (_buffered)
+				_refresh_buffered(x, y, w, h);
+
 			if (_sync_sigh.valid())
 				Signal_transmitter(_sync_sigh).submit();
 		}
 };
 
 
+static bool config_attribute(const char *attr_name)
+{
+	bool result = false;
+	try {
+		result =
+			Genode::config()->xml_node().attribute(attr_name).has_value("yes"); }
+	catch (...) {}
+	return result;
+}
+
+
 int main(int, char **)
 {
 	using namespace Framebuffer;
@@ -133,7 +185,8 @@ int main(int, char **)
 	/*
 	 * Let the entry point serve the framebuffer session and root interfaces
 	 */
-	static Session_component fb_session(driver, width, height, output);
+	static Session_component fb_session(driver, width, height, output,
+	                                    config_attribute("buffered"));
 	static Static_root<Framebuffer::Session> fb_root(ep.manage(&fb_session));
 
 	/*

repos/os/src/drivers/framebuffer/omap4/target.mk

@@ -7,7 +7,7 @@
 TARGET   = fb_drv
 REQUIRES = omap4
 SRC_CC   = main.cc
-LIBS     = base config
+LIBS     = base blit config
 INC_DIR += $(PRG_DIR)
 
 vpath main.cc $(PRG_DIR)