staging: comedi: cb_pcidas: tidy up dac08_write_insn()

For consistency with the other calib subdevices, refactor this (*insn_write)
function so that it only writes the final data value to the hardware.,

For aesthetics, rename the function so it has namespace associated with the
driver.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/cb_pcidas.c b/drivers/staging/comedi/drivers/cb_pcidas.c
index 86e3d200bb216f2fd914ff1323342837bef91115..04b6d39d10514aa7003424860db4f4e36e7171bf 100644 (file)
--- a/drivers/staging/comedi/drivers/cb_pcidas.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas.c
@@ -631,34 +631,35 @@ static int cb_pcidas_caldac_insn_write(struct comedi_device *dev,
 static void dac08_write(struct comedi_device *dev, unsigned int value)
 {
        struct cb_pcidas_private *devpriv = dev->private;
-       unsigned long cal_reg;
 
-       if (devpriv->dac08_value != value) {
-               devpriv->dac08_value = value;
+       value &= 0xff;
+       value |= cal_enable_bits(dev);
 
-               cal_reg = devpriv->control_status + CALIBRATION_REG;
-
-               value &= 0xff;
-               value |= cal_enable_bits(dev);
-
-               /* latch the new value into the caldac */
-               outw(value, cal_reg);
-               udelay(1);
-               outw(value | SELECT_DAC08_BIT, cal_reg);
-               udelay(1);
-               outw(value, cal_reg);
-               udelay(1);
-       }
+       /* latch the new value into the caldac */
+       outw(value, devpriv->control_status + CALIBRATION_REG);
+       udelay(1);
+       outw(value | SELECT_DAC08_BIT,
+            devpriv->control_status + CALIBRATION_REG);
+       udelay(1);
+       outw(value, devpriv->control_status + CALIBRATION_REG);
+       udelay(1);
 }
 
-static int dac08_write_insn(struct comedi_device *dev,
-                           struct comedi_subdevice *s,
-                           struct comedi_insn *insn, unsigned int *data)
+static int cb_pcidas_dac08_insn_write(struct comedi_device *dev,
+                                     struct comedi_subdevice *s,
+                                     struct comedi_insn *insn,
+                                     unsigned int *data)
 {
-       int i;
+       struct cb_pcidas_private *devpriv = dev->private;
+
+       if (insn->n) {
+               unsigned int val = data[insn->n - 1];
 
-       for (i = 0; i < insn->n; i++)
-               dac08_write(dev, data[i]);
+               if (devpriv->dac08_value != val) {
+                       dac08_write(dev, val);
+                       devpriv->dac08_value = val;
+               }
+       }
 
        return insn->n;
 }
@@ -1531,9 +1532,10 @@ static int cb_pcidas_auto_attach(struct comedi_device *dev,
                s->subdev_flags = SDF_READABLE | SDF_WRITABLE | SDF_INTERNAL;
                s->n_chan = NUM_CHANNELS_DAC08;
                s->insn_read = dac08_read_insn;
-               s->insn_write = dac08_write_insn;
+               s->insn_write = cb_pcidas_dac08_insn_write;
                s->maxdata = 0xff;
                dac08_write(dev, s->maxdata / 2);
+               devpriv->dac08_value = s->maxdata / 2;
        } else
                s->type = COMEDI_SUBD_UNUSED;