Comment 3 for bug 1120108

The patch I am mulling is:

diff --git a/src/sna/sna_render.c b/src/sna/sna_render.c
index 697b802..69ac21c 100644
--- a/src/sna/sna_render.c
+++ b/src/sna/sna_render.c
@@ -899,6 +899,9 @@ sna_render_pixmap_partial(struct sna *sna,
                DBG(("%s: tile size for tiling %d: %dx%d, size=%d\n",
                     __FUNCTION__, bo->tiling, tile_width, tile_height, tile_siz

+ if (sna->kgem.gen < 033)
+ tile_width = bo->pitch;
+
                /* Ensure we align to an even tile row */
                box.y1 = box.y1 & ~(2*tile_height - 1);
                box.y2 = ALIGN(box.y2, 2*tile_height);