There's no behavior change, but to prepare for the next img2buf blit improvement, except adding asserts to make clear of the existing blit code paths. v2: use switch with unreachable default per @gfxstrand has suggested Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35220>