Symbol: WREG8
sys/dev/pci/drm/amd/amdgpu/amdgpu.h
1474
#define WREG8(reg, v) amdgpu_mm_wreg8(adev, (reg), (v))
sys/dev/pci/drm/radeon/radeon.h
2547
#define WREG8(reg, v) writeb(v, (rdev->rmmio) + (reg))