[PATCH] EXA: fix mixed-pixmaps issue where we could do accel with pixmap mapped

skeggsb at gmail.com skeggsb at gmail.com
Fri Oct 23 17:45:49 PDT 2009

From: Ben Skeggs <bskeggs at redhat.com>

The problem occurs in the following situation:

1. Create Pixmap
2. Software fallback on pixmap: pExaPixmap->pDamage created
3. Accel to pixmap: driver pixmap created, exaPixmapIsOffscreen() now true
4. Software fallback on pixmap
4.1: PrepareAccess() from driver succeeds, so no DFS to system memory copy
4.2: Software rendering...
4.3: (pExaPixmap->pDamage && exaPixmapIsOffscreen()) is true, so we try
     to (incorrectly) UTS the data back to the driver pixmap, when we
     should just call the driver's FinishAccess() hook.
4.4: fail

The patch adds an additional check on pExaPixmap->offscreen, which should
(for the cases exaPixmapIsOffscreen() will return true) only be FALSE
when we haven't used PrepareAccess() on the pixmap.

Signed-off-by: Ben Skeggs <bskeggs at redhat.com>
Acked-By: Michel Dänzer <michel at daenzer.net>
 exa/exa_migration_mixed.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/exa/exa_migration_mixed.c b/exa/exa_migration_mixed.c
index f42c9c2..52b18b4 100644
--- a/exa/exa_migration_mixed.c
+++ b/exa/exa_migration_mixed.c
@@ -202,7 +202,8 @@ void exaFinishAccess_mixed(PixmapPtr pPixmap, int index)
-    if (pExaPixmap->pDamage && exaPixmapIsOffscreen(pPixmap)) {
+    if (pExaPixmap->pDamage && exaPixmapIsOffscreen(pPixmap) &&
+	!pExaPixmap->offscreen) {

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