Same here:

[    4.021250] amdgpu: [powerplay] amdgpu: powerplay sw initialized
[    4.067206] amdgpu: [powerplay] Can't find requested voltage id in
vdd_dep_on_sclk table!

Sapphire Nitro+ RX580 8 GB
amd-staging-4.11-1.g7262353-default

lspci -v show this:
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI]
Ellesmere [Radeon RX 470/480/570/580] (rev e7) (prog-if 00 [VGA controller])
        Subsystem: Sapphire Technology Limited Radeon RX 570

But it _is_ RX580 (Polaris 20).