Bug 1557266 - [Wayland] Use widget.wayland_dmabuf_backend.enabled preference to enable wayland dmabuf backend, r=jhorak

- Add widget.wayland_dmabuf_backend.enabled
- Expose it to Wayland backend by WaylandDisplay object
- Add more logging to Wayland DMABuf backend

Differential Revision: https://phabricator.services.mozilla.com/D33919

--HG--
extra : moz-landing-system : lando

modules/libpref/init/all.js

@@ -5070,6 +5070,11 @@ pref("gfx.xrender.enabled",false);
 pref("widget.content.allow-gtk-dark-theme", false);
 #endif
 #endif
+#ifdef MOZ_WAYLAND
+#ifdef HAVE_LIBDRM
+pref("widget.wayland_dmabuf_backend.enabled", false);
+#endif
+#endif
 
 pref("widget.window-transforms.disabled", false);
 

widget/gtk/WindowSurfaceWayland.cpp

@@ -420,6 +420,9 @@ WindowBackBufferDMABuf::WindowBackBufferDMABuf(
     nsWaylandDisplay* aWaylandDisplay, int aWidth, int aHeight)
     : WindowBackBuffer(aWaylandDisplay) {
   mDMAbufSurface.Create(aWidth, aHeight);
+
+  LOGWAYLAND(("%s [%p] Created DMABuf buffer [%d x %d]\n", __PRETTY_FUNCTION__,
+              (void*)this, aWidth, aHeight));
 }
 
 WindowBackBufferDMABuf::~WindowBackBufferDMABuf() { mDMAbufSurface.Release(); }
@@ -534,8 +537,8 @@ bool WindowSurfaceWayland::UseDMABufBackend() {
   if (!mUseDMABufInitialized) {
 #ifdef HAVE_LIBDRM
     if (WaylandDMABufSurface::IsAvailable()) {
-      mUseDMABuf =
-          Preferences::GetBool("gfx.wayland_dmabuf_backend.enabled", false);
+      mUseDMABuf = nsWaylandDisplay::IsDMABufEnabled();
+      LOGWAYLAND(("%s DMABuf state %d\n", __PRETTY_FUNCTION__, mUseDMABuf));
     }
 #endif
     mUseDMABufInitialized = true;

widget/gtk/nsWaylandDisplay.cpp

@@ -13,6 +13,11 @@ namespace widget {
 #define GBMLIB_NAME "libgbm.so.1"
 #define DRMLIB_NAME "libdrm.so.2"
 
+#ifdef HAVE_LIBDRM
+bool nsWaylandDisplay::mIsDMABufEnabled;
+bool nsWaylandDisplay::mIsDMABufPrefLoaded;
+#endif
+
 // nsWaylandDisplay needs to be created for each calling thread(main thread,
 // compositor thread and render thread)
 #define MAX_DISPLAY_CONNECTIONS 3
@@ -291,16 +296,23 @@ nsWaylandDisplay::nsWaylandDisplay(wl_display* aDisplay)
       ,
       mGbmDevice(nullptr),
       mGbmFd(-1),
-      mGdmConfigured(false),
-      mExplicitSync(false),
       mXRGBFormat({false, false, -1, nullptr, 0}),
-      mARGBFormat({false, false, -1, nullptr, 0})
+      mARGBFormat({false, false, -1, nullptr, 0}),
+      mGdmConfigured(false),
+      mExplicitSync(false)
 #endif
 {
   mRegistry = wl_display_get_registry(mDisplay);
   wl_registry_add_listener(mRegistry, &registry_listener, this);
 
   if (NS_IsMainThread()) {
+#ifdef HAVE_LIBDRM
+    if (!mIsDMABufPrefLoaded) {
+      mIsDMABufPrefLoaded = true;
+      mIsDMABufEnabled =
+          Preferences::GetBool("widget.wayland_dmabuf_backend.enabled", false);
+    }
+#endif
     // Use default event queue in main thread operated by Gtk+.
     mEventQueue = nullptr;
     wl_display_roundtrip(mDisplay);

widget/gtk/nsWaylandDisplay.h

@@ -68,16 +68,14 @@ class nsWaylandDisplay {
 #ifdef HAVE_LIBDRM
   void SetDmabuf(zwp_linux_dmabuf_v1* aDmabuf);
   zwp_linux_dmabuf_v1* GetDmabuf() { return mDmabuf; };
-
   gbm_device* GetGbmDevice();
-
   // Returns -1 if we fails to gbm device file descriptor.
   int GetGbmDeviceFd();
-
   bool IsExplicitSyncEnabled() { return mExplicitSync; }
   GbmFormat* GetGbmFormat(bool aHasAlpha);
   void AddFormatModifier(bool aHasAlpha, int aFormat, uint32_t mModifierHi,
                          uint32_t mModifierLo);
+  static bool IsDMABufEnabled() { return mIsDMABufEnabled; };
 #endif
 
  private:
@@ -99,10 +97,12 @@ class nsWaylandDisplay {
   zwp_linux_dmabuf_v1* mDmabuf;
   gbm_device* mGbmDevice;
   int mGbmFd;
-  bool mGdmConfigured;
-  bool mExplicitSync;
   GbmFormat mXRGBFormat;
   GbmFormat mARGBFormat;
+  bool mGdmConfigured;
+  bool mExplicitSync;
+  static bool mIsDMABufEnabled;
+  static bool mIsDMABufPrefLoaded;
 #endif
 };