egl/surfaceless: add probe device helper function

This will help us initialize a software driver, if it's needed
or requested.

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
diff --git a/src/egl/drivers/dri2/platform_surfaceless.c b/src/egl/drivers/dri2/platform_surfaceless.c
index 3c00ff4..f6aa217 100644
--- a/src/egl/drivers/dri2/platform_surfaceless.c
+++ b/src/egl/drivers/dri2/platform_surfaceless.c
@@ -267,6 +267,44 @@
    NULL,
 };
 
+static bool
+surfaceless_probe_device(_EGLDisplay *dpy)
+{
+   struct dri2_egl_display *dri2_dpy = dpy->DriverData;
+   const int limit = 64;
+   const int base = 128;
+   int fd;
+   int i;
+
+   for (i = 0; i < limit; ++i) {
+      char *card_path;
+      if (asprintf(&card_path, DRM_RENDER_DEV_NAME, DRM_DIR_NAME, base + i) < 0)
+         continue;
+
+      fd = loader_open_device(card_path);
+      free(card_path);
+      if (fd < 0)
+         continue;
+
+      dri2_dpy->driver_name = loader_get_driver_for_fd(fd);
+      if (!dri2_dpy->driver_name) {
+         close(fd);
+         continue;
+      }
+
+      dri2_dpy->fd = fd;
+      if (dri2_load_driver_dri3(dpy))
+         return true;
+
+      close(fd);
+      dri2_dpy->fd = -1;
+      free(dri2_dpy->driver_name);
+      dri2_dpy->driver_name = NULL;
+   }
+
+   return false;
+}
+
 EGLBoolean
 dri2_initialize_surfaceless(_EGLDriver *drv, _EGLDisplay *disp)
 {
@@ -282,34 +320,7 @@
 
    dri2_dpy->fd = -1;
    disp->DriverData = (void *) dri2_dpy;
-
-   const int limit = 64;
-   const int base = 128;
-   for (int i = 0; i < limit; ++i) {
-      char *card_path;
-      if (asprintf(&card_path, DRM_RENDER_DEV_NAME, DRM_DIR_NAME, base + i) < 0)
-         continue;
-
-      dri2_dpy->fd = loader_open_device(card_path);
-
-      free(card_path);
-      if (dri2_dpy->fd < 0)
-         continue;
-
-      dri2_dpy->driver_name = loader_get_driver_for_fd(dri2_dpy->fd);
-      if (dri2_dpy->driver_name) {
-         if (dri2_load_driver_dri3(disp)) {
-            driver_loaded = 1;
-            break;
-         }
-         free(dri2_dpy->driver_name);
-         dri2_dpy->driver_name = NULL;
-      }
-      close(dri2_dpy->fd);
-      dri2_dpy->fd = -1;
-   }
-
-   if (!driver_loaded) {
+   if (!surfaceless_probe_device(disp)) {
       err = "DRI2: failed to load driver";
       goto cleanup;
    }