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_classic.c

@@ -137,6 +137,10 @@ exaCreatePixmap_classic(ScreenPtr pScreen, int w, int h, int depth,
     exaSetAccelBlock(pExaScr, pExaPixmap,
                      w, h, bpp);
 
+    /* During a fallback we must prepare access. */
+    if (pExaScr->fallback_counter)
+	exaPrepareAccess(&pPixmap->drawable, EXA_PREPARE_AUX_DEST);
+
     return pPixmap;
 }
 
@@ -216,6 +220,10 @@ exaDestroyPixmap_classic (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 (pExaPixmap->area)
 	{
 	    DBG_PIXMAP(("-- 0x%p (0x%x) (%dx%d)\n",