exa: handle pixmap create/destroy in lower layers

- Pixmaps that are created during a fallback are automatically prepared access.
- During the fallback accelerated ops are blocked to prevent new/scratch gc's
  from triggering accelerated ops on mapped pixmaps.
- A few cases of incorrect wrapping (on the top level pointer instead of
  between damage and (w)fb) have been removed.

Signed-off-by: Maarten Maathuis <madman2003@gmail.com>
Acked-by: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Keith Packard <keithp@keithp.com>

exa/exa_mixed.c

@@ -97,6 +97,10 @@ exaCreatePixmap_mixed(ScreenPtr pScreen, int w, int h, int depth,
     } else
 	pExaPixmap->offscreen = FALSE;
 
+    /* During a fallback we must prepare access. */
+    if (pExaScr->fallback_counter)
+	exaPrepareAccess(&pPixmap->drawable, EXA_PREPARE_AUX_DEST);
+
     return pPixmap;
 }
 
@@ -188,6 +192,10 @@ exaDestroyPixmap_mixed(PixmapPtr pPixmap)
     {
 	ExaPixmapPriv (pPixmap);
 
+	/* During a fallback we must finish access, but we don't know the index. */
+	if (pExaScr->fallback_counter)
+	    exaFinishAccess(&pPixmap->drawable, -1);
+
 	if (pExaScr->deferred_mixed_pixmap == pPixmap)
 	    pExaScr->deferred_mixed_pixmap = NULL;