From: Colin Leroy <colin@colino.net>

Paulus brought this up on IRC, it seems to be a bad DRM merge: The code

#ifndef VMAP_4_ARGS
       if ( dev->agp->cant_use_aperture )
               return -EINVAL;
#endif

in DRM(agp_acquire) should be removed altogether in a 2.6 kernel because
its vmap() takes 4 arguments; however, only the guards seem to have been
removed, which causes this function to erroneously fail if the AGP aperture
can't be directly accessed by the CPU.
Signed-off-by: Colin Leroy <colin@colino.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>