(In reply to comment #4) > Is this a regression? Was dpm working previously at some point, if so when? Alex, I want to check this. What should I start from? You added si_dpm.c at 2013-06-27 (https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/log/drivers/gpu/drm/radeon/si_dpm.c?showmsg=1). Were there another system to change power management before? Is it enought to find first stable version available in ubuntu repo with si_dpm.c? Or should I use kernel from git and start bisect by history of si_dpm.c?