drm: fixup drm bufs being just under the EOM

If the mapping was just under the end of memory it would fail.
Lets DRM start on my PCI card.

Signed-off-by: Dave Airlie <airlied@linux.ie>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/char/drm/drm_bufs.c b/drivers/char/drm/drm_bufs.c
index 1845dd062816..1db12dcb6802 100644
--- a/drivers/char/drm/drm_bufs.c
+++ b/drivers/char/drm/drm_bufs.c
@@ -154,7 +154,7 @@ static int drm_addmap_core(drm_device_t * dev, unsigned int offset,
         case _DRM_REGISTERS:
         case _DRM_FRAME_BUFFER:
 #if !defined(__sparc__) && !defined(__alpha__) && !defined(__ia64__) && !defined(__powerpc64__) && !defined(__x86_64__)
-                if (map->offset + map->size < map->offset ||
+                if (map->offset + (map->size-1) < map->offset ||
                     map->offset < virt_to_phys(high_memory)) {
                         drm_free(map, sizeof(*map), DRM_MEM_MAPS);
                         return -EINVAL;