Since gen6, there has been a magic register bit to change the interpretation of the tiling mode between X and Y for BLT operations. With the advent of DRI3 and scanouts supporting Y, enabling support at last appears interesting, perhapss even by default for non-scanouts?
75d8776 sna: Enable blitting with Y-tiled surfaces
src/sna/gen6_common.h | 3 ++
src/sna/kgem.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++-
src/sna/kgem.h | 23 +++++++-
src/sna/sna_accel.c | 34 ++++++++++++
src/sna/sna_blt.c | 29 ++++++++--
src/sna/sna_io.c | 17 +++++-
6 files changed, 239 insertions(+), 8 deletions(-)
Upstream: cgit.freedesktop.org