Don't synchronize after each frame. Allow the GPU to be one frame

ahead of the CPU for more parallelism of CPU and GPU. Unfortunately
there seems to be some broken hardware (like my ProSavageDDR) on which
status register updates are delayed sometimes. This leads to very
jerky animation if the hardware can buffer more than the current
frame. A new option "sync_frames" can be used as a remedy on such
broken hardware.

3 files changed, 17 insertions, 14 deletions

diff --git a/src/mesa/drivers/dri/savage/savage_xmesa.c b/src/mesa/drivers/dri/savage/savage_xmesa.c
index 8e11ef2499..522c6275c4 100644
--- a/src/mesa/drivers/dri/savage/savage_xmesa.c
+++ b/src/mesa/drivers/dri/savage/savage_xmesa.c
@@ -69,6 +69,11 @@ DRI_CONF_OPT_BEGIN(enable_fastpath,bool,def) \
 	DRI_CONF_DESC(en,"Use fast path for unclipped primitives") \
 	DRI_CONF_DESC(de,"Schneller Codepfad für ungeschnittene Polygone") \
 DRI_CONF_OPT_END
+#define SAVAGE_SYNC_FRAMES(def) \
+DRI_CONF_OPT_BEGIN(sync_frames,bool,def) \
+	DRI_CONF_DESC(en,"Synchronize with graphics hardware after each frame") \
+	DRI_CONF_DESC(de,"Synchronisiere nach jedem Frame mit Grafikhardware") \
+DRI_CONF_OPT_END
 
 /* Configuration
  */
@@ -80,16 +85,17 @@ DRI_CONF_BEGIN
         DRI_CONF_FLOAT_DEPTH(false)
     DRI_CONF_SECTION_END
     DRI_CONF_SECTION_PERFORMANCE
-        DRI_CONF_MAX_TEXTURE_UNITS(2,1,2)
         SAVAGE_ENABLE_VDMA(true)
         SAVAGE_ENABLE_FASTPATH(true)
+        SAVAGE_SYNC_FRAMES(false)
+        DRI_CONF_MAX_TEXTURE_UNITS(2,1,2)
     	DRI_CONF_TEXTURE_HEAPS(DRI_CONF_TEXTURE_HEAPS_ALL)
     DRI_CONF_SECTION_END
     DRI_CONF_SECTION_DEBUG
         DRI_CONF_NO_RAST(false)
     DRI_CONF_SECTION_END
 DRI_CONF_END;
-static const GLuint __driNConfigOptions = 8;
+static const GLuint __driNConfigOptions = 9;
 
 #ifdef USE_NEW_INTERFACE
 static PFNGLXCREATECONTEXTMODES create_context_modes = NULL;
@@ -499,6 +505,8 @@ savageCreateContext( const __GLcontextModes *mesaVis,
    else
        imesa->enable_vdma = driQueryOptionb(&imesa->optionCache, "enable_vdma");
 
+   imesa->sync_frames = driQueryOptionb(&imesa->optionCache, "sync_frames");
+
    /* Configure swrast to match hardware characteristics:
     */
    _tnl_allow_pixel_fog( ctx, GL_FALSE );
diff --git a/src/mesa/drivers/dri/savage/savagecontext.h b/src/mesa/drivers/dri/savage/savagecontext.h
index 3bf688ce10..30a97150a8 100644
--- a/src/mesa/drivers/dri/savage/savagecontext.h
+++ b/src/mesa/drivers/dri/savage/savagecontext.h
@@ -301,6 +301,7 @@ struct savage_context_t {
     GLboolean float_depth;
     GLboolean enable_fastpath;
     GLboolean enable_vdma;
+    GLboolean sync_frames;
 };
 
 #define SAVAGE_CONTEXT(ctx) ((savageContextPtr)(ctx->DriverCtx))
diff --git a/src/mesa/drivers/dri/savage/savageioctl.c b/src/mesa/drivers/dri/savage/savageioctl.c
index 5399963cb9..9f3a028428 100644
--- a/src/mesa/drivers/dri/savage/savageioctl.c
+++ b/src/mesa/drivers/dri/savage/savageioctl.c
@@ -423,12 +423,6 @@ static void savageDDClear( GLcontext *ctx, GLbitfield mask, GLboolean all,
       _swrast_Clear( ctx, mask, all, cx, cy, cw, ch );
 }
 
-
-/* This is necessary to avoid very jerky animation on my ProSavageDDR.
- * Seems to work fine on other Savages though. Make this configurable!
- */
-#define SYNC_FRAMES 1
-
 /*
  * Copy the back buffer to the front buffer. 
  */
@@ -449,9 +443,9 @@ void savageSwapBuffers( __DRIdrawablePrivate *dPriv )
 
    FLUSH_BATCH(imesa);
 
-#if SYNC_FRAMES
-   imesa->lastSwap = savageEmitEvent( imesa, 0 );
-#endif
+   if (imesa->sync_frames)
+       imesa->lastSwap = savageEmitEvent( imesa, 0 );
+
    if (imesa->lastSwap != 0)
        savageWaitEvent( imesa, imesa->lastSwap );
 
@@ -463,9 +457,9 @@ void savageSwapBuffers( __DRIdrawablePrivate *dPriv )
        imesa->inSwap = GL_FALSE;
    }
 
-#if !SYNC_FRAMES
-   imesa->lastSwap = savageEmitEvent( imesa, 0 );
-#endif
+   if (!imesa->sync_frames)
+       /* don't sync, but limit the lag to one frame. */
+       imesa->lastSwap = savageEmitEvent( imesa, 0 );
 }
 
 unsigned int savageEmitEventLocked( savageContextPtr imesa, unsigned int flags )