rx 480 under linux support is dropped in 6.4 and 7.0 versions.
I'm getting:
Sep 11 17:42:51 rig3 kernel: [ 6802.533701] amdgpu 0000:05:00.0: GPU fault detected: 147 0x01f80801
Sep 11 17:42:51 rig3 kernel: [ 6802.534129] amdgpu 0000:05:00.0: VM_CONTEXT1_PROTECTION_FAULT_ADDR 0x0810483B
Sep 11 17:42:51 rig3 kernel: [ 6802.534567] amdgpu 0000:05:00.0: VM_CONTEXT1_PROTECTION_FAULT_STATUS 0x04084001
Sep 11 17:42:51 rig3 kernel: [ 6802.534997] VM fault (0x01, vmid 2) at page 135284795, read from 'TC7' (0x54433700) (132)
Now I'm using 6.3 version.