https://bugs.freedesktop.org/show_bug.cgi?id=73788
--- Comment #16 from Stepan Bakshaev step2back+freedesktop@gmail.com --- 1) checkout git://kernel.ubuntu.com/ubuntu/ubuntu-trusty.git 2) revert 4573388c92ee60b4ed72b8d95b73df861189988c 3) no error `si_set_sw_state failed`