https://bugs.freedesktop.org/show_bug.cgi?id=29833

--- Comment #16 from Alex Deucher agd5f@yahoo.com 2010-10-08 10:17:20 PDT --- (In reply to comment #10)

@Alex ok.. how can I check if this is the case?

enable state debugging and make sure the zs and zb state atoms are getting emitted. See radeon_print_state_atom() in radeon_common.c for more info.