DRI2: Expose API to set drawable swap limit.

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@nokia.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Reviewed-by: Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
index 1e6ee16a2..ae685bb0a 100644
--- a/hw/xfree86/dri2/dri2.c
+++ b/hw/xfree86/dri2/dri2.c
@@ -192,6 +192,29 @@ 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;