NV_PRMCIO_ARX
nvif_wr08(device, NV_PRMCIO_ARX + head * NV_PRMCIO_SIZE, enable ? 0 : 0x20);
return !(nvif_rd08(device, NV_PRMCIO_ARX + head * NV_PRMCIO_SIZE) & 0x20);
nvif_wr08(device, NV_PRMCIO_ARX + head * NV_PRMCIO_SIZE, index);
nvif_wr08(device, NV_PRMCIO_ARX + head * NV_PRMCIO_SIZE, index);