return ni_old_ao_config_chanlist(dev, s, chanspec, n_chans);
 }
 
-static int ni_ao_insn_read(struct comedi_device *dev,
-                          struct comedi_subdevice *s,
-                          struct comedi_insn *insn,
-                          unsigned int *data)
-{
-       struct ni_private *devpriv = dev->private;
-       unsigned int chan = CR_CHAN(insn->chanspec);
-       int i;
-
-       for (i = 0; i < insn->n; i++)
-               data[i] = devpriv->ao[chan];
-
-       return insn->n;
-}
-
 static int ni_ao_insn_write(struct comedi_device *dev,
                            struct comedi_subdevice *s,
                            struct comedi_insn *insn,
        for (i = 0; i < insn->n; i++) {
                unsigned int val = data[i];
 
-               devpriv->ao[chan] = val;
+               s->readback[chan] = val;
 
                if (devpriv->is_6xxx) {
                        /*
                s->n_chan       = board->n_aochan;
                s->maxdata      = board->ao_maxdata;
                s->range_table  = board->ao_range_table;
-               s->insn_read    = ni_ao_insn_read;
-               s->insn_write   = ni_ao_insn_write;
                s->insn_config  = ni_ao_insn_config;
+               s->insn_write   = ni_ao_insn_write;
+               s->insn_read    = comedi_readback_insn_read;
+
+               ret = comedi_alloc_subdev_readback(s);
+               if (ret)
+                       return ret;
 
                /*
                 * Along with the IRQ we need either a FIFO or DMA for