SRCTL
tmp = read_chan(dev, SRCTL, 0);
write_chan(dev, SRCTL, 0, tmp);
tmp = read_chan(dev, SRCTL, 0) & ~0x0303c00f;
write_chan(dev, SRCTL, 0, tmp);
write_chan(dev, SRCTL, 1, 0x30303030);
write_chan(dev, SRCTL, 1, 0xffff0000 | r << 8 | r);