A similar issue occurs with a Radeon RX 470...
[ 13.348522] [drm] amdgpu kernel modesetting enabled. [ 13.576111] amdgpu 0000:81:00.0: firmware: direct-loading firmware amdgpu/polaris10_mc.bin [ 13.576450] amdgpu 0000:81:00.0: VRAM: 4096M 0x0000000000000000 - 0x00000000FFFFFFFF (4096M used) [ 13.576456] amdgpu 0000:81:00.0: GTT: 258006M 0x0000000100000000 - 0x0000003FFD67A7FF [ 13.576519] [drm] amdgpu: 4096M of VRAM memory ready [ 13.576522] [drm] amdgpu: 258006M of GTT memory ready. [ 13.576733] [drm:amdgpu_device_init [amdgpu]] *ERROR* sw_init of IP block <gmc_v8_0> failed -12 [ 13.576820] amdgpu 0000:81:00.0: amdgpu_init failed [ 13.576886] amdgpu 0000:81:00.0: Fatal error during GPU init [ 13.576950] [drm] amdgpu: finishing device. [ 13.578186] amdgpu: probe of 0000:81:00.0 failed with error -12 -------------------------- 81:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480] (rev ef) (prog-if 00 [VGA controller]) Subsystem: XFX Pine Group Inc. Ellesmere [Radeon RX 470/480] Physical Slot: 8 Flags: fast devsel, IRQ 26, NUMA node 6 Memory at e0000000 (64-bit, prefetchable) [size=256M] Memory at dfe00000 (64-bit, prefetchable) [size=2M] I/O ports at 5000 [size=256] Memory at fdfc0000 (32-bit, non-prefetchable) [size=256K] [virtual] Expansion ROM at 000c0000 [disabled] [size=128K] Capabilities: [48] Vendor Specific Information: Len=08 <?> Capabilities: [50] Power Management version 3 Capabilities: [58] Express Legacy Endpoint, MSI 00 Capabilities: [a0] MSI: Enable- Count=1/1 Maskable- 64bit+ Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?> Capabilities: [150] Advanced Error Reporting Capabilities: [200] #15 Capabilities: [270] #19 Capabilities: [2b0] Address Translation Service (ATS) Capabilities: [2c0] Page Request Interface (PRI) Capabilities: [2d0] Process Address Space ID (PASID) Capabilities: [320] Latency Tolerance Reporting Capabilities: [328] Alternative Routing-ID Interpretation (ARI) Capabilities: [370] L1 PM Substates Kernel modules: amdgpu