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>

diff --git a/drivers/char/drm/drm_bufs.c b/drivers/char/drm/drm_bufs.c
index 1845dd0..1db12dc 100644 (file)
--- 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;