PFBS
write_chan(dev, PFBS, 0, chunksz << 16);
write_chan(dev, PFBS, 1, chunksz << 16);
write_chan(dev, PFBS, 3, chunksz << 16);
write_reg(dev, PFBS, 0, chunksz << 16);
write_reg(dev, PFBS, 1, chunksz << 16);
write_reg(dev, PFBS, 2, chunksz << 16);