exa: increase/rework safety checks in Prepare/FinishAccess.

1 files changed, 5 insertions, 0 deletions

diff --git a/exa/exa.h b/exa/exa.h
index 8339a3e44..d7219f053 100644
--- a/exa/exa.h
+++ b/exa/exa.h
@@ -695,6 +695,11 @@ typedef struct _ExaDriver {
     /* Hooks to allow driver to its own pixmap memory management */
     void *(*CreatePixmap)(ScreenPtr pScreen, int size, int align);
     void (*DestroyPixmap)(ScreenPtr pScreen, void *driverPriv);
+    /**
+     * Returning a pixmap with non-NULL devPrivate.ptr implies a pixmap which is
+     * not offscreen, which will never be accelerated and Prepare/FinishAccess won't
+     * be called.
+     */
     Bool (*ModifyPixmapHeader)(PixmapPtr pPixmap, int width, int height,
                               int depth, int bitsPerPixel, int devKind,
                               pointer pPixData);