vrend: Use server side fence wait.

Change to use eglWaitSyncKHR which is a server side fence and it
could be sightly better.

Signed-off-by: Lepton Wu <lepton@chromium.org>
Reviewed-by: David Riley <davidriley@chromium.org>

src/virgl_egl.h

@@ -58,5 +58,6 @@ void *virgl_egl_aux_plane_image_from_dmabuf(struct virgl_egl *egl, struct gbm_bo
 void virgl_egl_image_destroy(struct virgl_egl *egl, void *image);
 
 bool virgl_egl_need_fence_and_wait_external(struct virgl_egl *egl);
-void virgl_egl_fence_and_wait_external(struct virgl_egl *egl);
+void *virgl_egl_fence(struct virgl_egl *egl);
+void virgl_egl_wait_fence(struct virgl_egl *egl, void* fence);
 #endif

src/virgl_egl_context.c

@@ -518,21 +518,25 @@ bool virgl_egl_need_fence_and_wait_external(struct virgl_egl *egl)
    return (egl && egl->need_fence_and_wait_external);
 }
 
-void virgl_egl_fence_and_wait_external(struct virgl_egl *egl)
+void *virgl_egl_fence(struct virgl_egl *egl)
 {
    const EGLint attrib_list[] = {EGL_SYNC_CONDITION_KHR,
                                  EGL_SYNC_PRIOR_COMMANDS_COMPLETE_KHR,
                                  EGL_NONE};
-   EGLSyncKHR fence;
+   EGLSyncKHR fence = EGL_NO_SYNC_KHR;
 
    if (!egl || !has_bit(egl->extension_bits, EGL_KHR_FENCE_SYNC)) {
-      return;
+      return (void *)fence;
    }
 
-   fence = eglCreateSyncKHR(egl->egl_display, EGL_SYNC_FENCE_KHR, attrib_list);
-   if (fence != EGL_NO_SYNC_KHR) {
-      eglClientWaitSyncKHR(egl->egl_display, fence,
-                           EGL_SYNC_FLUSH_COMMANDS_BIT_KHR, EGL_FOREVER_KHR);
-      eglDestroySyncKHR(egl->egl_display, fence);
-   }
+   return (void *)eglCreateSyncKHR(egl->egl_display, EGL_SYNC_FENCE_KHR, attrib_list);
+}
+
+void virgl_egl_wait_fence(struct virgl_egl *egl, void* sync)
+{
+   EGLSyncKHR fence = (EGLSyncKHR) sync;
+   if (fence == EGL_NO_SYNC_KHR)
+      return;
+   eglWaitSyncKHR(egl->egl_display, fence, 0);
+   eglDestroySyncKHR(egl->egl_display, fence);
 }

src/vrend_renderer.c

@@ -7633,12 +7633,13 @@ int vrend_renderer_transfer_iov(const struct vrend_transfer_info *info,
       return EINVAL;
    }
 
+   void* fence = NULL;
 #ifdef HAVE_EPOXY_EGL_H
    // Some platforms require extra synchronization before transferring.
    if (transfer_mode == VIRGL_TRANSFER_FROM_HOST) {
       if (virgl_egl_need_fence_and_wait_external(egl)) {
          vrend_hw_switch_context(ctx, true);
-         virgl_egl_fence_and_wait_external(egl);
+         fence = virgl_egl_fence(egl);
       }
    }
 #endif
@@ -7675,6 +7676,7 @@ int vrend_renderer_transfer_iov(const struct vrend_transfer_info *info,
 
    if (info->context0) {
       vrend_renderer_force_ctx_0();
+      virgl_egl_wait_fence(egl, fence);
       ctx = NULL;
    }