EXA: Handle separate alpha maps properly in Composite fallback, take two.

Preserve the EXA ABI by introducing a new driver flag EXA_SUPPORTS_PREPARE_AUX.
If the driver doesn't set this flag, we have to assume any Prepare/FinishAccess
driver hooks can't handle the EXA_PREPARE_AUX* indices, so we move out such
pixmaps at PrepareAccess time.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=18710 .

Signed-off-by: Michel Dänzer <daenzer@vmware.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/exa/exa.c b/exa/exa.c
index a64769905..5425f902e 100644
--- a/exa/exa.c
+++ b/exa/exa.c
@@ -538,6 +538,12 @@ ExaDoPrepareAccess(DrawablePtr pDrawable, int index)
     if (pExaScr->info->PrepareAccess == NULL)
 	return;
 
+    if (index >= EXA_PREPARE_AUX0 &&
+	!(pExaScr->info->flags & EXA_SUPPORTS_PREPARE_AUX)) {
+	exaMoveOutPixmap (pPixmap);
+	return;
+    }
+
     if (!(*pExaScr->info->PrepareAccess) (pPixmap, index)) {
 	ExaPixmapPriv (pPixmap);
 	if (pExaPixmap->score == EXA_PIXMAP_SCORE_PINNED)
@@ -597,6 +603,13 @@ exaFinishAccess(DrawablePtr pDrawable, int index)
     if (!exaPixmapIsOffscreen (pPixmap))
 	return;
 
+    if (index >= EXA_PREPARE_AUX0 &&
+	!(pExaScr->info->flags & EXA_SUPPORTS_PREPARE_AUX)) {
+	ErrorF("EXA bug: Trying to call driver FinishAccess hook with "
+	       "unsupported index EXA_PREPARE_AUX*\n");
+	return;
+    }
+
     (*pExaScr->info->FinishAccess) (pPixmap, index);
 }