https://bugs.freedesktop.org/show_bug.cgi?id=90595
--- Comment #7 from JATothrim jarmo.tiitto@gmail.com --- (In reply to Adam Flott from comment #6)
(In reply to JATothrim from comment #5)
I am also a victim of this bug. It freezes/soft bricks my machine every time while resuming from hibernate - suspend to ram tough works kind of ok (tty dual monitor border corruption). I'm running 4.2.0 vanilla kernel.
Try upgrading xf86-video-ati from git. You only need to cp the src/.libs/radeon_drv.so file to /usr/lib/xorg/modules/drivers/radeon_drv.so (or your distros equivalent). Beware that X will auto-restart afterwards. I found that doing so has squashed Bug91994. However I still see [drm:si_dpm_set_power_state [radeon]] *ERROR* si_set_sw_state failed in dmesg.
I'm already using newest git mesa (Oibaf graphics drivers ppa). I also have tied self compiling the git mesa driver but no change to hibernate. However I disabled the radeon DPM power management with radeon.dpm=0 in kernel command-line and it fixed the hibernate! I still see awful lot of this '[drm:si_dpm_set_power_state [radeon]] *ERROR* si_set_sw_state failed' error in dmesg tough. Also bad is that I miss the automatic DPM..