By failing to set the errno, we'd continue on to trying to set up the
RCL, and then oops on trying to dereference the tile_bo that binning
validation should have set up.
Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Eric Anholt <eric@anholt.net> Fixes: d5b1a78a772f ("drm/vc4: Add support for drawing 3D frames.")