1. We can create resource with size of "1" on drm, because size
is not passed to the renderer.
2. We can't create resource with size of "1" on vtest, because shmem
is created based on that.
3. If renderer supports copy_transfer_from_host, then use staging
buffer for transfer in both ways to and from host.
This will allow to reduce memory consumption in the guest.
v2:
- add inline function for checking if we can use this optimization
- add check in readback path. If renderer doesn't support
copy transfer from host, then we need to go with previous
path in readback (through transfer_get ioctl)
v3:
- fix logic for readback
v4:
- refactor the implementation to integrate it more to
existing code base
v5:
- reuse COPY_TRANSFER3D in both directions
v6:
- encode direction in COPY_TRANSFER3D if host supports it
v7:
- renamed cap bit
- introduced COPY_TRANSFER3D_SIZE_LEGACY define
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13689>
cdc480585c