Refactor and fix core vblank support

Consolidate support for synchronizing to and retrieving vblank counters.  Also
fix the core vblank code to return monotonic MSC counters, which are required
by some GLX extensions.  Adding support for multiple pipes to a low level
driver is fairly easy, the Intel 965 driver provides simple example code (see
intel_buffers.c:intelWindowMoved()).

The new code bumps the media stream counter extension version to 2 and adds a
new getDrawableMSC callback.  This callback takes a drawablePrivate pointer,
which is used to calculate the MSC value seen by clients based on the actual
vblank counter(s) returned from the kernel.  The new drawable private fields
are as follows:
  - vblSeq - used for tracking vblank counts for buffer swapping
  - vblFlags - flags (e.g. current pipe), updated by low level driver
  - msc_base - MSC counter from the last time the current pipe changed
  - vblank_base - kernel DRM vblank counter from the last time the pipe changed

Using the above variables, the core vblank code (in vblank.c) can calculate a
monotonic MSC value.  The low level DRI drivers are responsible for updating
the current pipe (by setting VBLANK_FLAG_SECONDARY for example in vblFlags)
along with msc_base and vblank_base whenever the pipe associated with a given
drawable changes (again, see intelWindowMoved for an example of this).

Drivers should fill in the GetDrawableMSC DriverAPIRec field to point to
driDrawableGetMSC32 and add code for pipe switching as outlined above to fully
support the new scheme.

1 files changed, 26 insertions, 17 deletions

diff --git a/src/glx/x11/glxcmds.c b/src/glx/x11/glxcmds.c
index 707e398d1d6..7e8a0c146d5 100644
--- a/src/glx/x11/glxcmds.c
+++ b/src/glx/x11/glxcmds.c
@@ -1941,13 +1941,24 @@ static int __glXGetVideoSyncSGI(unsigned int *count)
    if ( (gc != NULL) && gc->isDirect ) {
       __GLXscreenConfigs * const psc = GetGLXScreenConfigs( gc->currentDpy,
 							    gc->screen );
-      if (psc->msc != NULL && psc->driScreen.private != NULL) {
-	 int       ret;
-	 int64_t   temp;
-
-	 ret = psc->msc->getMSC(&psc->driScreen, &temp);
-	 *count = (unsigned) temp;
-	 return (ret == 0) ? 0 : GLX_BAD_CONTEXT;
+      if ( psc->msc && psc->driScreen.private ) {
+          __DRIdrawable * const pdraw = 
+              GetDRIDrawable(gc->currentDpy, gc->currentDrawable, NULL);
+	  int64_t temp; 
+	  int ret;
+ 
+ 	  /*
+ 	   * Try to use getDrawableMSC first so we get the right
+ 	   * counter...
+ 	   */
+	  if (psc->msc->base.version >= 2 && psc->msc->getDrawableMSC)
+	      ret = (*psc->msc->getDrawableMSC)( &psc->driScreen,
+						 pdraw->private,
+						 & temp);
+	  else
+	      ret = (*psc->msc->getMSC)( &psc->driScreen, & temp);
+	  *count = (unsigned) temp;
+	  return (ret == 0) ? 0 : GLX_BAD_CONTEXT;
       }
    }
 #else
@@ -1970,16 +1981,14 @@ static int __glXWaitVideoSyncSGI(int divisor, int remainder, unsigned int *count
       if (psc->msc != NULL && psc->driScreen.private ) {
 	 __DRIdrawable * const pdraw = 
 	     GetDRIDrawable(gc->currentDpy, gc->currentDrawable, NULL);
-	 if (pdraw != NULL) {
-	    int       ret;
-	    int64_t   msc;
-	    int64_t   sbc;
-
-	    ret = (*psc->msc->waitForMSC)(pdraw, 0,
-					  divisor, remainder, &msc, &sbc);
-	    *count = (unsigned) msc;
-	    return (ret == 0) ? 0 : GLX_BAD_CONTEXT;
-	 }
+	 int       ret;
+	 int64_t   msc;
+	 int64_t   sbc;
+
+	 ret = (*psc->msc->waitForMSC)(pdraw, 0, divisor, remainder, &msc,
+				       &sbc);
+	 *count = (unsigned) msc;
+	 return (ret == 0) ? 0 : GLX_BAD_CONTEXT;
       }
    }
 #else