From 394a162738f30f9cbf975f93bb9e15399715c423 Mon Sep 17 00:00:00 2001
From: "Owen W. Taylor" <otaylor@fishsoup.net>
Date: Mon, 12 Nov 2012 11:52:31 -0500
Subject: Prefer OML_sync_control over SGI_video_sync when waiting for swap

When we block waiting for the swap, prefer doing that using
glXWaitForMsc() from OML_sync_control because that returns a system
time value for the precise time of the swap.
---
 cogl/winsys/cogl-winsys-glx-feature-functions.h | 23 +++++++++++++++++
 cogl/winsys/cogl-winsys-glx.c                   | 34 ++++++++++++++++++++-----
 2 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/cogl/winsys/cogl-winsys-glx-feature-functions.h b/cogl/winsys/cogl-winsys-glx-feature-functions.h
index 44d45321..f06ac69a 100644
--- a/cogl/winsys/cogl-winsys-glx-feature-functions.h
+++ b/cogl/winsys/cogl-winsys-glx-feature-functions.h
@@ -129,6 +129,29 @@ COGL_WINSYS_FEATURE_FUNCTION (int, glXSwapInterval,
                               (int interval))
 COGL_WINSYS_FEATURE_END ()
 
+COGL_WINSYS_FEATURE_BEGIN (255, 255,
+                           sync_control,
+                           "OML\0",
+                           "sync_control\0",
+                           0,
+                           0)
+COGL_WINSYS_FEATURE_FUNCTION (Bool, glXGetSyncValues,
+                              (Display* dpy,
+                               GLXDrawable drawable,
+                               int64_t* ust,
+                               int64_t* msc,
+                               int64_t* sbc))
+COGL_WINSYS_FEATURE_FUNCTION (Bool, glXWaitForMsc,
+                              (Display* dpy,
+                               GLXDrawable drawable,
+                               int64_t target_msc,
+                               int64_t divisor,
+                               int64_t remainder,
+                               int64_t* ust,
+                               int64_t* msc,
+                               int64_t* sbc))
+COGL_WINSYS_FEATURE_END ()
+
 COGL_WINSYS_FEATURE_BEGIN (255, 255,
                            copy_sub_buffer,
                            "MESA\0",
diff --git a/cogl/winsys/cogl-winsys-glx.c b/cogl/winsys/cogl-winsys-glx.c
index e9bf7f0e..5b092e0e 100644
--- a/cogl/winsys/cogl-winsys-glx.c
+++ b/cogl/winsys/cogl-winsys-glx.c
@@ -428,10 +428,12 @@ update_base_winsys_features (CoglRenderer *renderer)
                   COGL_WINSYS_FEATURE_MULTIPLE_ONSCREEN,
                   TRUE);
 
-  if (glx_renderer->glXWaitVideoSync)
+  if (glx_renderer->pf_glXWaitVideoSync ||
+      glx_renderer->pf_glXWaitForMsc)
     COGL_FLAGS_SET (glx_renderer->base_winsys_features,
                     COGL_WINSYS_FEATURE_VBLANK_WAIT,
                     TRUE);
+
 }
 
 static CoglBool
@@ -1254,14 +1256,32 @@ _cogl_winsys_wait_for_vblank (CoglContext *ctx)
 
   glx_renderer = ctx->display->renderer->winsys;
 
-  if (glx_renderer->glXGetVideoSync)
+  if (glx_renderer->glXWaitForMsc ||
+      glx_renderer->glXGetVideoSync)
     {
-      uint32_t current_count;
+      if (glx_renderer->glXWaitForMsc)
+        {
+          CoglOnscreenGLX *glx_onscreen = onscreen->winsys;
+          Drawable drawable = glx_onscreen->glxwin;
+          int64_t ust;
+          int64_t msc;
+          int64_t sbc;
+
+          glx_renderer->glXGetSyncValues (xlib_renderer->xdpy, drawable,
+                                          &ust, &msc, &sbc);
+          glx_renderer->glXWaitForMsc (xlib_renderer->xdpy, drawable,
+                                       0, 2, (msc + 1) % 2,
+                                       &ust, &msc, &sbc);
+        }
+      else
+        {
+          uint32_t current_count;
 
-      glx_renderer->glXGetVideoSync (&current_count);
-      glx_renderer->glXWaitVideoSync (2,
-                                      (current_count + 1) % 2,
-                                      &current_count);
+          glx_renderer->glXGetVideoSync (&current_count);
+          glx_renderer->glXWaitVideoSync (2,
+                                          (current_count + 1) % 2,
+                                          &current_count);
+        }
     }
 }
 
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