[Ozone] Adding HardwareDisplayController implementation

ui/gfx/ozone/impl/hardware_display_controller_ozone.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_GFX_OZONE_IMPL_HARDWARE_DISPLAY_CONTROLLER_OZONE_H_
+#define UI_GFX_OZONE_IMPL_HARDWARE_DISPLAY_CONTROLLER_OZONE_H_
+
+#include <stddef.h>
+#include <stdint.h>
+#include <xf86drmMode.h>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/gfx/ozone/impl/drm_wrapper_ozone.h"
+
+namespace gfx {
+
+class SoftwareSurfaceOzone;
+
+// The HDCOz will handle modesettings and scannout operations for hardware
+// devices.
+//
+// In the DRM world there are 3 components that need to be paired up to be able
+// to display an image to the monitor: CRTC (cathode ray tube controller),
+// encoder and connector. The CRTC determines which framebuffer to read, when
+// to scanout and where to scanout. Encoders converts the stream from the CRTC
+// to the appropriate format for the connector. The connector is the physical
+// connection that monitors connect to.
+//
+// There is no 1:1:1 pairing for these components. It is possible for an encoder
+// to be compatible to multiple CRTCs and each connector can be used with
+// multiple encoders. In addition, it is possible to use one CRTC with multiple
+// connectors such that we can display the same image on multiple monitors.
+//
+// For example, the following configuration shows 2 different screens being
+// initialized separately.
+// -------------      -------------
+// | Connector |      | Connector |
+// |   HDMI    |      |    VGA    |
+// -------------      -------------
+//       ^                  ^
+//       |                  |
+// -------------      -------------
+// |  Encoder1  |     |  Encoder2 |
+// -------------      -------------
+//       ^                  ^
+//       |                  |
+// -------------      -------------
+// |   CRTC1   |      |   CRTC2   |
+// -------------      -------------
+//
+// In the following configuration 2 different screens are associated with the
+// same CRTC, so on scanout the same framebuffer will be displayed on both
+// monitors.
+// -------------      -------------
+// | Connector |      | Connector |
+// |   HDMI    |      |    VGA    |
+// -------------      -------------
+//       ^                  ^
+//       |                  |
+// -------------      -------------
+// |  Encoder1  |     |  Encoder2 |
+// -------------      -------------
+//       ^                  ^
+//       |                  |
+//      ----------------------
+//      |        CRTC1       |
+//      ----------------------
+//
+// Note that it is possible to have more connectors than CRTCs which means that
+// only a subset of connectors can be active independently, showing different
+// framebuffers. Though, in this case, it would be possible to have all
+// connectors active if some use the same CRTC to mirror the display.
+//
+// TODO(dnicoara) Need to have a way to detect events (such as monitor
+// connected or disconnected).
+class HardwareDisplayControllerOzone {
+ public:
+  // Controller states. The state transitions will happen from top to bottom.
+  enum State {
+    // When we allocate a HDCO as a stub. At this point there is no connector
+    // and CRTC associated with this device.
+    UNASSOCIATED,
+
+    // When |SetControllerInfo| is called and the HDCO has the information of
+    // the hardware it will control. At this point it knows everything it needs
+    // to control the hardware but doesn't have a surface.
+    UNINITIALIZED,
+
+    // A surface is associated with the HDCO. This means that the controller can
+    // potentially display the backing surface to the display. Though the
+    // surface framebuffer still needs to be registered with the CRTC.
+    SURFACE_INITIALIZED,
+
+    // The CRTC now knows about the surface attributes.
+    INITIALIZED,
+
+    // Error state if any of the initialization steps fail.
+    FAILED,
+  };
+
+  HardwareDisplayControllerOzone();
+
+  ~HardwareDisplayControllerOzone();
+
+  // Set the hardware configuration for this HDCO. Once this is set, the HDCO is
+  // responsible for keeping track of the connector and CRTC and cleaning up
+  // when it is destroyed.
+  void SetControllerInfo(DrmWrapperOzone* drm,
+                         uint32_t connector_id,
+                         uint32_t crtc_id,
+                         drmModeModeInfo mode);
+
+  // Associate the HDCO with a surface implementation and initialize it.
+  bool BindSurfaceToController(SoftwareSurfaceOzone* surface);
+
+  // Schedules the |surface_|'s framebuffer to be displayed on the next vsync
+  // event. The event will be posted on the graphics card file descriptor |fd_|
+  // and it can be read and processed by |drmHandleEvent|. That function can
+  // define the callback for the page flip event. A generic data argument will
+  // be presented to the callback. We use that argument to pass in the HDCO
+  // object the event belongs to.
+  //
+  // Between this call and the callback, the framebuffer used in this call
+  // should not be modified in any way as it would cause screen tearing if the
+  // hardware performed the flip. Note that the frontbuffer should also not
+  // be modified as it could still be displayed.
+  //
+  // Note that this function does not block. Also, this function should not be
+  // called again before the page flip occurrs.
+  //
+  // Returns true if the page flip was successfully registered, false otherwise.
+  bool SchedulePageFlip();
+
+  State get_state() const { return state_; };
+
+  int get_fd() const { return drm_->get_fd(); };
+
+  const drmModeModeInfo& get_mode() const { return mode_; };
+
+  SoftwareSurfaceOzone* get_surface() const { return surface_.get(); };
+
+ private:
+  // Object containing the connection to the graphics device and wraps the API
+  // calls to control it.
+  DrmWrapperOzone* drm_;
+
+  // TODO(dnicoara) Need to allow a CRTC to have multiple connectors.
+  uint32_t connector_id_;
+
+  uint32_t crtc_id_;
+
+  // TODO(dnicoara) Need to store all the modes.
+  drmModeModeInfo mode_;
+
+  // Saved CRTC state from before we used it. Need it to restore state once we
+  // are finished using this device.
+  drmModeCrtc* saved_crtc_;
+
+  State state_;
+
+  scoped_ptr<SoftwareSurfaceOzone> surface_;
+
+  DISALLOW_COPY_AND_ASSIGN(HardwareDisplayControllerOzone);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_OZONE_IMPL_HARDWARE_DISPLAY_CONTROLLER_OZONE_H_