Question about glxBindTexImageExt()


I need to display an X11 pixmap in an opengl view so I want to use the function glxBindTexImageExt().

My concern is about when to call the function glxBindTexImageEx() because the content of the X11 pixmap is regularly updated. Shall I call glxBindTexImageEx() once at the creation of the texture or do I need to call it whenever the content of the X11 pixmap changes in order to synchronize texture with the content of the pixmap?