https://bugs.freedesktop.org/show_bug.cgi?id=97260
--- Comment #9 from Alex Deucher alexdeucher@gmail.com --- (In reply to Kai from comment #8)
(In reply to Alex Deucher from comment #6)
Does reverting 5e031d9fe8b0741f11d49667dfc3ebf5454121fd (drm/radeon/pm: update current crtc info after setting the powerstate) help?
No, it does not for me (I fetched the patch from https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/ ?id=5e031d9fe8b0741f11d49667dfc3ebf5454121fd and applied it with patch -p1 -R < /path/to.patch). The Talos Principle is still down to 43 FPS, haven't tested XCOM 2 or anything else.
Btw, not sure if it can help tracking down the cause: the GPU doesn't seem to go into its highest performance mode or at least the fan is not reaching its highest RPM when I'm on 4.7.0 (with or without the revert).
You can check by running apps and monitoring the content of /sys/kernel/debug/dri/64/radeon_pm_info Do you see it scaling up under load on the problematic kernels? Does forcing the clocks to high via sysfs work ok?