And assign the initial width and height to the minimum in that case.
Strange values (-1) from these registers have been reported by users.
Signed-off-by: NThomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: NJakob Bornecrantz <jakob@vmware.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>