[PATCH 1/2] Patch to the Xserver to support AsyncSwap

[Axel Davy]

The patch is a modified version of a Chris Wilson patch of 2011.
It makes the X server call AsyncSwap, defined by the DDX, when
it does a dri2 swap and swap_interval is 0. It allows the DDX
to avoid the copy if possible, and reduce tearings.

Signed-off-by: Axel Davy <axel.davy at ens.fr>
---
 hw/xfree86/dri2/dri2.c | 36 ++++++++++++++++++++++++------------
 hw/xfree86/dri2/dri2.h |  8 +++++++-
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
index 483d630..7b06da9 100644
--- a/hw/xfree86/dri2/dri2.c
+++ b/hw/xfree86/dri2/dri2.c
@@ -118,6 +118,7 @@ typedef struct _DRI2Screen {
     DRI2CreateBufferProcPtr CreateBuffer;
     DRI2DestroyBufferProcPtr DestroyBuffer;
     DRI2CopyRegionProcPtr CopyRegion;
+    DRI2AsyncSwapProcPtr AsyncSwap;
     DRI2ScheduleSwapProcPtr ScheduleSwap;
     DRI2GetMSCProcPtr GetMSC;
     DRI2ScheduleWaitMSCProcPtr ScheduleWaitMSC;
@@ -1107,20 +1108,30 @@ DRI2SwapBuffers(ClientPtr client, DrawablePtr pDraw, CARD64 target_msc,
 
     /* Old DDX or no swap interval, just blit */
     if (!ds->ScheduleSwap || !pPriv->swap_interval || pPriv->prime_id) {
-        BoxRec box;
-        RegionRec region;
-
-        box.x1 = 0;
-        box.y1 = 0;
-        box.x2 = pDraw->width;
-        box.y2 = pDraw->height;
-        RegionInit(&region, &box, 0);
-
         pPriv->swapsPending++;
 
-        dri2_copy_region(pDraw, &region, pDestBuffer, pSrcBuffer);
-        DRI2SwapComplete(client, pDraw, target_msc, 0, 0, DRI2_BLIT_COMPLETE,
-                         func, data);
+        if (ds->AsyncSwap)
+        {
+            (*ds->AsyncSwap)(client, pDraw,
+                             pDestBuffer, pSrcBuffer,
+                             func, data);
+            DRI2InvalidateDrawableAll(pDraw);
+        }
+        else
+        {
+            BoxRec box;
+            RegionRec region;
+
+            box.x1 = 0;
+            box.y1 = 0;
+            box.x2 = pDraw->width;
+            box.y2 = pDraw->height;
+            RegionInit(&region, &box, 0);
+
+            dri2_copy_region(pDraw, &region, pDestBuffer, pSrcBuffer);
+            DRI2SwapComplete(client, pDraw, target_msc, 0, 0,
+                             DRI2_BLIT_COMPLETE, func, data);
+        }
         return Success;
     }
 
@@ -1463,6 +1474,7 @@ DRI2ScreenInit(ScreenPtr pScreen, DRI2InfoPtr info)
 
     if (info->version >= 10) {
         ds->AuthMagic = info->AuthMagic3;
+        ds->AsyncSwap = info->AsyncSwap;
     }
     if (info->version >= 8) {
         ds->LegacyAuthMagic2 = info->AuthMagic2;
diff --git a/hw/xfree86/dri2/dri2.h b/hw/xfree86/dri2/dri2.h
index ed67d01..f376e42 100644
--- a/hw/xfree86/dri2/dri2.h
+++ b/hw/xfree86/dri2/dri2.h
@@ -52,7 +52,12 @@ extern CARD8 dri2_minor;
 typedef DRI2BufferRec DRI2Buffer2Rec, *DRI2Buffer2Ptr;
 typedef void (*DRI2SwapEventPtr) (ClientPtr client, void *data, int type,
                                   CARD64 ust, CARD64 msc, CARD32 sbc);
-
+typedef void (*DRI2AsyncSwapProcPtr)(ClientPtr client,
+                                     DrawablePtr pDraw,
+                                     DRI2BufferPtr pDestBuffer,
+                                     DRI2BufferPtr pSrcBuffer,
+                                     DRI2SwapEventPtr func,
+                                     void *data);
 typedef DRI2BufferPtr(*DRI2CreateBuffersProcPtr) (DrawablePtr pDraw,
                                                   unsigned int *attachments,
                                                   int count);
@@ -257,6 +262,7 @@ typedef struct {
 
     /* added in version 10 */
     DRI2AuthMagic3ProcPtr AuthMagic3;
+    DRI2AsyncSwapProcPtr AsyncSwap;
 } DRI2InfoRec, *DRI2InfoPtr;
 
 extern _X_EXPORT Bool DRI2ScreenInit(ScreenPtr pScreen, DRI2InfoPtr info);
-- 
1.8.1.2