drm/radeon: also try GART for CPU accessed buffers

Placing them exclusively into VRAM might not work all the time.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=78297

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/radeon_object.c

@@ -699,22 +699,30 @@ int radeon_bo_fault_reserve_notify(struct ttm_buffer_object *bo)
 	rbo = container_of(bo, struct radeon_bo, tbo);
 	radeon_bo_check_tiling(rbo, 0, 0);
 	rdev = rbo->rdev;
-	if (bo->mem.mem_type == TTM_PL_VRAM) {
+	if (bo->mem.mem_type != TTM_PL_VRAM)
+		return 0;
+
 	size = bo->mem.num_pages << PAGE_SHIFT;
 	offset = bo->mem.start << PAGE_SHIFT;
-		if ((offset + size) > rdev->mc.visible_vram_size) {
+	if ((offset + size) <= rdev->mc.visible_vram_size)
+		return 0;
+
 	/* hurrah the memory is not visible ! */
 	radeon_ttm_placement_from_domain(rbo, RADEON_GEM_DOMAIN_VRAM);
 	rbo->placement.lpfn = rdev->mc.visible_vram_size >> PAGE_SHIFT;
 	r = ttm_bo_validate(bo, &rbo->placement, false, false);
-			if (unlikely(r != 0))
+	if (unlikely(r == -ENOMEM)) {
+		radeon_ttm_placement_from_domain(rbo, RADEON_GEM_DOMAIN_GTT);
+		return ttm_bo_validate(bo, &rbo->placement, false, false);
+	} else if (unlikely(r != 0)) {
 		return r;
+	}
+
 	offset = bo->mem.start << PAGE_SHIFT;
-			/* this should not happen */
+	/* this should never happen */
 	if ((offset + size) > rdev->mc.visible_vram_size)
 		return -EINVAL;
-		}
-	}
+
 	return 0;
 }