[PATCH xserver/dri2 3/3] DRI2SwapBuffers: Return SBC correctly, handle target_msc correctly.

[Mario Kleiner]

Returns expected SBC after completion of swap to caller, as required
by OML_sync_control spec, instead of the last_swap_target value.

Passes target_msc, divisor, remainder, correctly for
glXSwapBuffersMscOML() call, while retaining old
behaviour for simple glXSwapBuffers() call.

Signed-off-by: Mario Kleiner <mario.kleiner at tuebingen.mpg.de>
---
 hw/xfree86/dri2/dri2.c |   43 +++++++++++++++++++++++++++++--------------
 1 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
index 7f40d28..453bc6b 100644
--- a/hw/xfree86/dri2/dri2.c
+++ b/hw/xfree86/dri2/dri2.c
@@ -597,33 +597,43 @@ DRI2SwapBuffers(ClientPtr client, DrawablePtr pDraw, CARD64 target_msc,
 	return Success;
     }
 
-    /*
-     * In the simple glXSwapBuffers case, all params will be 0, and we just
-     * need to schedule a swap for the last swap target + the swap interval.
+    /* First swap needs to initialize last_swap_target.
      * If the last swap target hasn't been set yet, call into the driver
      * to get the current count.
      */
-    if (target_msc == 0 && divisor == 0 && remainder == 0 &&
-	pPriv->last_swap_target < 0) {
-	ret = (*ds->GetMSC)(pDraw, &ust, &target_msc);
+    if (pPriv->last_swap_target < 0) {
+       ret = (*ds->GetMSC)(pDraw, &ust, &pPriv->last_swap_target);
 	if (!ret) {
 	    xf86DrvMsg(pScreen->myNum, X_ERROR,
 		       "[DRI2] %s: driver failed to return current MSC\n",
 		       __func__);
+	    pPriv->last_swap_target = -1;
 	    return BadDrawable;
 	}
     }
 
-    /* First swap needs to initialize last_swap_target */
-    if (pPriv->last_swap_target < 0)
-	pPriv->last_swap_target = target_msc;
-
     /*
-     * Swap target for this swap is last swap target + swap interval since
-     * we have to account for the current swap count, interval, and the
-     * number of pending swaps.
+     * In the simple glXSwapBuffers case, all params will be 0, and we just
+     * need to schedule a swap for the last swap target + the swap interval.
      */
-    *swap_target = pPriv->last_swap_target + pPriv->swap_interval;
+    if (target_msc == 0 && divisor == 0 && remainder == 0) {
+        /*
+         * Swap target for this swap is last swap target + swap interval since
+         * we have to account for the current swap count, interval, and the
+         * number of pending swaps.
+         */
+        *swap_target = pPriv->last_swap_target + pPriv->swap_interval;
+    }
+    else {
+        /* glXSwapBuffersMscOML() call with target_msc, divisor, remainder set.
+         * Just make sure that target_msc is not earlier than last swap target +
+         * swap interval.
+         */
+        if (target_msc < pPriv->last_swap_target + pPriv->swap_interval)
+	    target_msc = pPriv->last_swap_target + pPriv->swap_interval;
+	
+        *swap_target = target_msc;
+    }
 
     ret = (*ds->ScheduleSwap)(client, pDraw, pDestBuffer, pSrcBuffer,
 			      swap_target, divisor, remainder, func, data);
@@ -636,6 +646,11 @@ DRI2SwapBuffers(ClientPtr client, DrawablePtr pDraw, CARD64 target_msc,
     pPriv->swapsPending++;
     pPriv->last_swap_target = *swap_target;
 
+    /* According to spec, return expected swapbuffers count SBC after this swap
+     * will complete.
+     */
+    *swap_target = pPriv->swap_count + pPriv->swapsPending;
+
     return Success;
 }
 
-- 
1.6.6