[PATCH] DRI2: Expose API to set drawable swap limit.

[Pauli Nieminen]

This allows ddx to set swap_limit if there is more than one back
buffer for drawable. Setting swap_limit has to also check if change
affects a client that is blocked.

This can be used to implement N-buffering in driver with minimal
logic in allocation and selecting next back.

Signed-off-by: Pauli Nieminen <ext-pauli.nieminen at nokia.com>
Tested-by: Francisco Jerez <currojerez at riseup.net>
CC: Kristian Høgsberg <krh at bitplanet.net>
CC: Jesse Barnes <jbarnes at virtuousgeek.org>
---
 hw/xfree86/dri2/dri2.c |   23 +++++++++++++++++++++++
 hw/xfree86/dri2/dri2.h |    1 +
 2 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
index 34f735f..c96eb35 100644
--- a/hw/xfree86/dri2/dri2.c
+++ b/hw/xfree86/dri2/dri2.c
@@ -190,6 +190,29 @@ DRI2AllocateDrawable(DrawablePtr pDraw)
     return pPriv;
 }
 
+Bool
+DRI2SwapLimit(DrawablePtr pDraw, int swap_limit)
+{
+    DRI2DrawablePtr pPriv = DRI2GetDrawable(pDraw);
+    if (!pPriv)
+	return FALSE;
+
+    pPriv->swap_limit = swap_limit;
+
+    /* Check throttling */
+    if (pPriv->swapsPending >= pPriv->swap_limit)
+	return TRUE;
+
+    if (pPriv->target_sbc == -1 && !pPriv->blockedOnMsc) {
+	if (pPriv->blockedClient) {
+	    AttendClient(pPriv->blockedClient);
+	    pPriv->blockedClient = NULL;
+	}
+    }
+
+    return TRUE;
+}
+
 typedef struct DRI2DrawableRefRec {
     XID		  id;
     XID		  dri2_id;
diff --git a/hw/xfree86/dri2/dri2.h b/hw/xfree86/dri2/dri2.h
index fe0bf6c..0e0bea4 100644
--- a/hw/xfree86/dri2/dri2.h
+++ b/hw/xfree86/dri2/dri2.h
@@ -251,6 +251,7 @@ extern _X_EXPORT DRI2BufferPtr *DRI2GetBuffersWithFormat(DrawablePtr pDraw,
 	int *out_count);
 
 extern _X_EXPORT void DRI2SwapInterval(DrawablePtr pDrawable, int interval);
+extern _X_EXPORT Bool DRI2SwapLimit(DrawablePtr pDraw, int swap_limit);
 extern _X_EXPORT int DRI2SwapBuffers(ClientPtr client, DrawablePtr pDrawable,
 				     CARD64 target_msc, CARD64 divisor,
 				     CARD64 remainder, CARD64 *swap_target,
-- 
1.7.0.4