1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/char/drm/drm_bufs.c b/drivers/char/drm/drm_bufs.c
index 07b774fa3f38..bde64b84166e 100644
--- a/drivers/char/drm/drm_bufs.c
+++ b/drivers/char/drm/drm_bufs.c
@@ -229,11 +229,17 @@ static int drm_addmap_core(struct drm_device * dev, unsigned int offset,
 #ifdef __alpha__
                 map->offset += dev->hose->mem_space->start;
 #endif
-                /* Note: dev->agp->base may actually be 0 when the DRM
-                 * is not in control of AGP space. But if user space is
-                 * it should already have added the AGP base itself.
+                /* In some cases (i810 driver), user space may have already
+                 * added the AGP base itself, because dev->agp->base previously
+                 * only got set during AGP enable.  So, only add the base
+                 * address if the map's offset isn't already within the
+                 * aperture.
                  */
-                map->offset += dev->agp->base;
+                if (map->offset < dev->agp->base ||
+                    map->offset > dev->agp->base +
+                    dev->agp->agp_info.aper_size * 1024 * 1024 - 1) {
+                        map->offset += dev->agp->base;
+                }
                 map->mtrr = dev->agp->agp_mtrr; /* for getmap */
 
                 /* This assumes the DRM is in total control of AGP space.