staging: comedi: cb_pcidas: cleanup dac08_write()

Reverse the logic of the test against the cached value so that
the function only has one exit point.

Make the logic of the dac write a bit clearer by create a local
variable for the address used in the outw() calls and masking the
value to write and setting the enable bits before doing the outw()
calls. Add a comment just to make sure it's clear.

Also, add a comment about the 'return 1;'.  This should be
insn->n which is the number of data parameters used to do the
dac08_write_insn() but the insn is not a parameter to this
function.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: 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 1479325ab7ea898e940f36d816c3bc5fef697782..3ba75afe4e05833827646334bd53497e4c36e348 100644 (file)
--- a/drivers/staging/comedi/drivers/cb_pcidas.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas.c
@@ -662,23 +662,25 @@ static int caldac_read_insn(struct comedi_device *dev,
 static int 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)
-               return 1;
+       if (devpriv->dac08_value != value) {
+               devpriv->dac08_value = value;
 
-       devpriv->dac08_value = value;
+               cal_reg = devpriv->control_status + CALIBRATION_REG;
 
-       outw(cal_enable_bits(dev) | (value & 0xff),
-            devpriv->control_status + CALIBRATION_REG);
-       udelay(1);
-       outw(cal_enable_bits(dev) | SELECT_DAC08_BIT | (value & 0xff),
-            devpriv->control_status + CALIBRATION_REG);
-       udelay(1);
-       outw(cal_enable_bits(dev) | (value & 0xff),
-            devpriv->control_status + CALIBRATION_REG);
-       udelay(1);
+               value &= 0xff;
+               value |= cal_enable_bits(dev);
 
-       return 1;
+               /* 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);
+       }
+       return 1;       /* insn->n */
 }
 
 static int dac08_write_insn(struct comedi_device *dev,