egl: Allow a prioritized list of default drivers

When there is no user driver or any matching display drivers we fall
back to the default driver.  This patch lets us have a list of default
drivers instead of just one.  The drivers are loaded in turn and we
attempt to initialize the display.  If it fails we unload the driver
and move on to the next one.

Compared to the display driver mechanism, this avoids loading a number
of drivers and then only using one.  Also, we call Initialize to see
if the driver will work instead of relying on Probe.  To know for sure
that a driver will work, Probe really have to do a full Initialize, so
we will just use Initialize directly.

6 files changed, 45 insertions, 26 deletions

diff --git a/src/egl/main/eglapi.c b/src/egl/main/eglapi.c
index 647be652207..f57dda88833 100644
--- a/src/egl/main/eglapi.c
+++ b/src/egl/main/eglapi.c
@@ -272,13 +272,15 @@ eglInitialize(EGLDisplay dpy, EGLint *major, EGLint *minor)
       if (!drv) {
          _eglPreloadDrivers();
          drv = _eglMatchDriver(disp);
-         if (!drv)
-            RETURN_EGL_ERROR(disp, EGL_NOT_INITIALIZED, EGL_FALSE);
+	 /* Initialize the particular display now */
+	 if (drv && !drv->API.Initialize(drv, disp, &major_int, &minor_int))
+	    RETURN_EGL_ERROR(disp, EGL_NOT_INITIALIZED, EGL_FALSE);
       }
-
-      /* Initialize the particular display now */
-      if (!drv->API.Initialize(drv, disp, &major_int, &minor_int))
-         RETURN_EGL_ERROR(disp, EGL_NOT_INITIALIZED, EGL_FALSE);
+      if (!drv)
+	 /* Load and initialize the first default driver that works */
+	 drv = _eglLoadDefaultDriver(disp, &major_int, &minor_int);
+      if (!drv)
+	 RETURN_EGL_ERROR(disp, EGL_NOT_INITIALIZED, EGL_FALSE);
 
       disp->APImajor = major_int;
       disp->APIminor = minor_int;
diff --git a/src/egl/main/eglconfig.c b/src/egl/main/eglconfig.c
index 21d13cba904..47513a4edb2 100644
--- a/src/egl/main/eglconfig.c
+++ b/src/egl/main/eglconfig.c
@@ -13,7 +13,6 @@
 
 
 #define MIN2(A, B)  (((A) < (B)) ? (A) : (B))
-#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
 
 
 /**
diff --git a/src/egl/main/egldefines.h b/src/egl/main/egldefines.h
index 8fc2301b795..4ecd4c1420c 100644
--- a/src/egl/main/egldefines.h
+++ b/src/egl/main/egldefines.h
@@ -40,6 +40,7 @@
 
 #define _EGL_VENDOR_STRING "Mesa Project"
 
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
 
 
 #endif /* EGLDEFINES_INCLUDED */
diff --git a/src/egl/main/egldriver.c b/src/egl/main/egldriver.c
index 2913ce2ece9..566554d51dc 100644
--- a/src/egl/main/egldriver.c
+++ b/src/egl/main/egldriver.c
@@ -36,7 +36,9 @@
 
 
 /* XXX Need to decide how to do dynamic name lookup on Windows */
-static const char DefaultDriverName[] = "TBD";
+static const char DefaultDriverNames[] = {
+   "TBD",
+};
 
 typedef HMODULE lib_handle;
 
@@ -63,7 +65,10 @@ library_suffix(void)
 #elif defined(_EGL_PLATFORM_POSIX)
 
 
-static const char DefaultDriverName[] = "egl_glx";
+static const char *DefaultDriverNames[] = {
+   "egl_dri2",
+   "egl_glx"
+};
 
 typedef void * lib_handle;
 
@@ -488,17 +493,6 @@ _eglPreloadDisplayDrivers(void)
 
 
 /**
- * Preload the default driver.
- */
-static EGLBoolean
-_eglPreloadDefaultDriver(void)
-{
-   return (_eglPreloadForEach(_eglGetSearchPath(),
-            _eglLoaderFile, (void *) DefaultDriverName) > 0);
-}
-
-
-/**
  * Preload drivers.
  *
  * This function loads the driver modules and creates the corresponding
@@ -519,15 +513,13 @@ _eglPreloadDrivers(void)
    }
 
    loaded = (_eglPreloadUserDriver() ||
-             _eglPreloadDisplayDrivers() ||
-             _eglPreloadDefaultDriver());
+             _eglPreloadDisplayDrivers());
 
    _eglUnlockMutex(_eglGlobal.Mutex);
 
    return loaded;
 }
 
-
 /**
  * Unload preloaded drivers.
  */
@@ -558,6 +550,30 @@ _eglUnloadDrivers(void)
    _eglGlobal.NumDrivers = 0;
 }
 
+_EGLDriver *
+_eglLoadDefaultDriver(EGLDisplay dpy, EGLint *major, EGLint *minor)
+{
+   _EGLDriver *drv = NULL;
+   int i;
+
+   _eglLockMutex(_eglGlobal.Mutex);
+
+   for (i = 0; i < ARRAY_SIZE(DefaultDriverNames); i++) {
+      _eglPreloadForEach(_eglGetSearchPath(),
+			 _eglLoaderFile, (void *) DefaultDriverNames[i]);
+      if (_eglGlobal.NumDrivers == 0)
+	 continue;
+      drv = _eglGlobal.Drivers[0];
+      if (drv->API.Initialize(drv, dpy, major, minor))
+	 break;
+      _eglUnloadDrivers();
+   }      
+
+   _eglUnlockMutex(_eglGlobal.Mutex);
+
+   return drv;
+}
+
 
 /**
  * Plug all the available fallback routines into the given driver's
diff --git a/src/egl/main/egldriver.h b/src/egl/main/egldriver.h
index 28b79562f80..8b34c43b924 100644
--- a/src/egl/main/egldriver.h
+++ b/src/egl/main/egldriver.h
@@ -84,6 +84,10 @@ extern void
 _eglUnloadDrivers(void);
 
 
+extern _EGLDriver *
+_eglLoadDefaultDriver(EGLDisplay dpy, EGLint *major, EGLint *minor);
+
+
 PUBLIC void
 _eglInitDriverFallbacks(_EGLDriver *drv);
 
diff --git a/src/egl/main/eglglobals.c b/src/egl/main/eglglobals.c
index 5182b18e226..e63819e08a2 100644
--- a/src/egl/main/eglglobals.c
+++ b/src/egl/main/eglglobals.c
@@ -6,9 +6,6 @@
 #include "eglmutex.h"
 
 
-#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
-
-
 static _EGL_DECLARE_MUTEX(_eglGlobalMutex);
 struct _egl_global _eglGlobal =
 {