https://bugs.freedesktop.org/show_bug.cgi?id=91880
--- Comment #67 from Alex Deucher alexdeucher@gmail.com --- (In reply to Julian from comment #65)
sclk_dpm_key_disabled = 1; mclk_dpm_key_disabled = 0; pcie_dpm_key_disabled = 1; thermal_sclk_dpm_enabled = 1; ==> NO LOCKUP - however, I periodically checked /sys/kernel/debug/dri/0/radeon_pm_info and mclk never actually changed (always 150000). Maybe mclk usually always changes based on sclk? With slck locked, mclk wouldn't change either, even if unlocked.
What are you testing with? You may not be producing enough memory load.