(In reply to Alex Deucher from comment #7)
> Can you bisect to figure out what commit broke things for you?

Okay, here is the result from bisect:

b92c628712ed3a1cf5d4a144290e8ffc170bf51e is the first bad commit
commit b92c628712ed3a1cf5d4a144290e8ffc170bf51e
Author: Rex Zhu <Rex.Zhu@amd.com>
Date:   Tue Jun 5 13:06:11 2018 +0800

    drm/amd/pp: Unify powergate_uvd/vce/mmhub to set_powergating_by_smu

    Some HW ip blocks need call SMU to enter/leave power gate state.
    So export common set_powergating_by_smu interface.

    1. keep consistent with set_clockgating_by_smu
    2. scales easily to powergate other ip(gfx) if necessary

    Reviewed-by: Evan Quan <evan.quan@amd.com>
    Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

:040000 040000 cf80741fafed463d93a0d41d85f267ff8c3859ca
2daca62d7af472048be8e0911c39e9a26fe376c0 M      drivers

Let me know if there's anything more I can do to help. I'll take a look at the
code but like I said I'm not a kernel developer so it's unlikely I'll
understand it or be able to fix it.