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 1479325..3ba75af 100644
--- a/drivers/staging/comedi/drivers/cb_pcidas.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas.c
@@ -662,23 +662,25 @@
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,