RADEON_TEST_DEBUG_MUX
WREG32(RADEON_TEST_DEBUG_MUX, (RREG32(RADEON_TEST_DEBUG_MUX) & 0xffff60ff) | 0x100);
WREG32(RADEON_TEST_DEBUG_MUX, RREG32(RADEON_TEST_DEBUG_MUX) & 0xffffe0ff);