https://bugzilla.kernel.org/show_bug.cgi?id=206347
Bug ID: 206347 Summary: amdgpu.dc=1 breaks power management on RX480 Product: Drivers Version: 2.5 Kernel Version: 5.4.14 Hardware: x86-64 OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: Video(DRI - non Intel) Assignee: drivers_video-dri@kernel-bugs.osdl.org Reporter: matare@fh-aachen.de Regression: No
I've been using an AMD RX480 with amdgpu ever since it was supported (i.e. since ~4.8 I think). Somehow I almost got used to the fact that, when idling, it uses 15-20 Watt more than in Windows. Recently I investigated again and found that it simply never reduces the GPU clock below 1278Mhz.
I found this related bug report on freedesktop.org: https://gitlab.freedesktop.org/drm/amd/issues/817
And this comment on Phoronix... https://www.phoronix.com/forums/forum/linux-graphics-x-org-drivers/open-sour...
... which gave the crucial hint of setting amdgpu.dc=0
It is only with this setting that my GPU clock will be reduced to 300 MHz on idle as it should. My system runs perfectly fine, performance is good, and system idle power consumption is down to ~70W from the ~90W I had before. So I don't understand why we're wasting 20W by default on all those chips. Maybe there is something that should be fixed or it should default to off?